# TDS Protocol Documentation

This document attempts to cover the TDS protocol for:

TDS Version | Supported Products
4.2 | Sybase SQL Server < 10 and Microsoft SQL Server 6.5
5.0 | Sybase SQL Server >= 10
7.0 | Microsoft SQL Server 7.0
7.1 | Microsoft SQL Server 2000
7.2 | Microsoft SQL Server 2005

## Contents

- Common Terms
- Typical Usage Sequences
- The Packet Format
- Login Packet
- TDS 7.0 Login Packet
- Collation structure
- Client requests
- Server Responses
- OCBC stored procedures (by jtds)

## Common Terms

    TDS protocol versions
      TDS 5.0    tds version 5.0
      TDS 7.0    tds version 7.0
      TDS 7.0+   tds version 7.0, 7.1 and 7.2
      TDS 5.0-   tds version 5.0 and previous

    Variable types used in this document:
      CHAR      8-bit char
        CHAR[6]	string of 6 chars
        CHAR[n]     variable length string
      XCHAR    single byte (TDS 5.0-) or ucs2le (TDS 7.0+) characters
      INT8      8-bit int
      INT16    16-bit int
      INT32    32-bit int
      UCS2LE   Unicode in UCS2LE format

Note: FreeTDS uses TDS_TINYINT for INT8 and TDS_SMALLINT for INT16.

## Typical Usage sequences

These are TDS 4.2 and not meant to be 100% correct, but I thought they might be helpful to get an overall view of what goes on.

    --> Login
    <-- Login acknowledgement

    --> INSERT SQL statement
    <-- Result Set Done

    --> SELECT SQL statement
    <-- Column Names
    <-- Column Info
    <-- Row Result
    <-- Row Result
    <-- Result Set Done

    --> call stored procedure
    <-- Column Names
    <-- Column Info
    <-- Row Result
    <-- Row Result
    <-- Done Inside Process
    <-- Column Names
    <-- Column Info
    <-- Row Result
    <-- Row Result
    <-- Done Inside Process
    <-- Return Status
    <-- Process Done

## The packet format

Every informations in TDS protocol (query, RPCs, responses and so on) is splitted in packets.

All packets start with the following 8 byte header.

     INT8       INT8          INT16      4 bytes
    +----------+-------------+----------+--------------------+
    |  packet  | last packet |  packet  |    unknown         |
    |   type   |  indicator  |   size   |                    |
    +----------+-------------+----------+--------------------+

    Fields:
    packet type
         0x01 TDS 4.2 or 7.0 query
         0x02 TDS 4.2 or 5.0 login packet
         0x03 RPC
         0x04 responses from server
         0x06 cancels
         0x07 Used in Bulk Copy
         0x0F TDS 5.0 query
         0x10 TDS 7.0 login packet
         0x11 TDS 7.0 authentication packet
         0x12 TDS 8 prelogin packet
    last packet indicator
         0x00 if more packets
         0x01 if last packet
    packet size
         (in network byte order)
    unknown?
         always 0x00
         this has something to do with server to server communication/rpc stuff

The remainder of the packet depends on the type of information it is providing. As noted above, packets break down into the types query, login, response, and cancels. Response packets are further split into multiple sub-types denoted by the first byte (a.k.a. the token) following the above header.

Note: A TDS packet that is longer than 512 bytes is split on the 512 byte boundary and the "more packets" bit is set. The full TDS packet is reassembled from its component 512 byte packets with the 8-byte headers stripped out. 512 is the block_size in the login packet, so it could be set to a different values. In Sybase you can configure a range of valid block sizes. TDS 7.0+ use a default of 4096 as block size.

## TDS 4.2 & 5.0 Login Packet

Packet type (first byte) is 2. The numbers on the left are decimal offsets including the 8 byte packet header.

    byte   var type    description
    ------------------------------
       8   CHAR[30]    host_name
      38   INT8        host_name_length
      39   CHAR[30]    user_name
      69   INT8        user_name_length
      70   CHAR[30]    password
     100   INT8        password_length
     101   CHAR[30]    host_process
     131   INT8        host_process_length
     132   ?           magic1[6]          /* mystery stuff */
     138   INT8        bulk_copy
     139   ?           magic2[9]          /* mystery stuff */
     148   CHAR[30]    app_name
     178   INT8        app_name_length
     179   CHAR[30]    server_name
     209   INT8        server_name_length
     210   ?           magic3[1]          /* 0, don't know this one either */
     211   INT8        password2_length
     212   CHAR[30]    password2
     242   CHAR[223]   magic4
     465   INT8        password2_length_plus2
     466   INT16       major_version      /* TDS version */
     468   INT16       minor_version      /* TDS version */
     470   CHAR        library_name[10]   /* "Ct-Library" or "DB-Library" */
     480   INT8        library_length
     481   INT16       major_version2     /* program version */
     483   INT16       minor_version2     /* program version */
     485   ?           magic6[3]          /* ? last two octets are 13 and 17 */
                                          /* bdw reports last two as 12 and 16 here  */
                                          /* possibly a bitset flag  */
     488   CHAR[30]    language           /* e.g. "us-english" */
     518   INT8        language_length
     519   ?           magic7[1]          /*  mystery stuff */
     520   INT16       old_secure         /* explanation? */
     522   INT8        encrypted          /*  1 means encrypted all password fields blank */
     523   ?           magic8[1]          /*  no clue... zeros */
     524   CHAR        sec_spare[9]       /* explanation? */
     533   CHAR[30]    char_set           /* e.g. "iso_1" */
     563   INT8        char_set_length
     564   INT8        magic9[1]          /* 1 */
     565   CHAR[6]     block_size         /*  in text */
     571   INT8        block_size_length
     572   ?           magic10[25]        /* lots of stuff here...no clue */

Any help with the magic numbers would be most appreciated.

## TDS 7.0+ Login Packet

    byte  var type  description
    ---------------------------
      0   INT32	total packet size
      4   INT8[4]	TDS Version
                    	0x00000070 7.0
    			0x01000071 7.1
                    	0x02000972 7.2 (7.2.9?)
      8   INT32	packet size (default 4096)
     12   INT8[4]	client program version
     16   INT32	PID of client
     20   INT32	connection id (usually 0)
     24   INT8	option flags 1
                    0x80 enable warning messages if SET LANGUAGE issued
                    0x40 change to initial database must succeed
                    0x20 enable warning messages if USE <database> issued
                    0x10 enable BCP
    		0x08 use ND5000 floating point format (untested)
    		0x04 use VAX floating point format (untested)
    		0x02 use EBCDIC encoding (untested)
    		0x01 use big-endian byte order (untested)
     25   INT8	option flags 2
                    0x80 enable domain login security
    		0x40 "USER_SERVER - reserved"
    		0x20 user type is "DQ login"
    		0x10 user type is "replication login"
    		0x08 "fCacheConnect"
    		0x04 "fTranBoundary"
                    0x02 client is an ODBC driver
                    0x01 change to initial language must succeed
     26   INT8	0x04 spawn user instance (TDS 7.2)
                    0x02 XML data type instances are returned as binary XML (TDS 7.2)
                    0x01 password change requested (TDS 7.2)
     27   INT8	0x01 SQL Type: 0 = use default, 1 = use T-SQL (TDS 7.2)
     28   INT8[4]	time zone (0x88ffffff ???)
     32   INT8[4]	collation information
     36   INT16	position of client hostname (86)
     38   INT16	hostname length
     40   INT16	position of username
     42   INT16	username length
     44   INT16	position of password
     46   INT16	password length
     48   INT16	position of app name
     50   INT16	app name length
     52   INT16	position of server name
     54   INT16	server name length
     56   INT16	position of remote server/password pairs
     58   INT16	remote server/password pairs length
     60   INT16	position of library name
     62   INT16	library name length
     64   INT16	position of language
     66   INT16	language name (for italian "Italiano", coded UCS2)
     68   INT16	position of database name
     70   INT16	database name length
     72   INT8[6]	MAC address of client
     78   INT16	position of auth portion
     80   INT16	NT authentication length
     82   INT16	next position (same as total packet size)
     84   INT16	0
     86   UCS2LE[n] hostname
          UCS2LE[n]	username
          UCS2LE[n]	encrypted password
          UCS2LE[n]	app name
          UCS2LE[n]	server name
          UCS2LE[n]	library name
          UCS2LE[n]	language name
          UCS2LE[n]	database name
          NT Authentication packet

    NT Authentication packet
      0   CHAR[8]	authentication id "NTLMSSP\0"
      8   INT32     1  message type
     12   INT32	0xb201 flags
     16   INT16	domain length
     18   INT16     domain length
     20   INT32     domain offset
     24   INT16     hostname length
     26   INT16     hostname length
     28   INT32     hostname offset
     32   CHAR[n]   hostname
          CHAR[n]   domain
    See documentation on Samba for detail (or search ntlm authentication for IIS)

    For mssql 2005 before hostname (byte 86) you have
     86   INT16     next position,  or
                    position of file name for a database to be
                    attached during the connection process
     88   INT16     database filename length
     90   INT16     new password position
     92   INT16     new password length
     94   UCS2LE[n] hostname
          ... (as above)

"current pos" is the starting byte address for a Unicode string within the packet. The length of that Unicode string immediately follows. That implies there are at least 2 more strings that could be defined. (character set??)

Username and password are empty if domain authentication is used.

If the client uses an authentication packet, the server replies with an Authentication token followed by an Authentication packet.

## TDS 7.0 Authentication Packet

     varies
    +------+
    | auth |
    +------+

    auth   authentication data
           for NTLM this message 3

This packet usually follows Authentication token.

## Types

HEX | DEC | type | protocol | nullable | size | collate
--- | --- | --- | --- | --- | --- | ---
0x1F | 31 | SYBVOID | 7+ | no | 0 |
0x22 | 34 | SYBIMAGE |  | yes | 4 |
0x23 | 35 | SYBTEXT |  | yes | 4 | yes
0x24 | 36 | SYBUNIQUE | 7+ | yes | 1 |
0x25 | 37 | SYBVARBINARY |  | yes | 1 |
0x26 | 38 | SYBINTN |  | yes | 1 |
0x27 | 39 | SYBVARCHAR |  | yes | 1 |
0x2D | 45 | SYBBINARY |  | yes | 1 |
0x2F | 47 | SYBCHAR |  | yes | 1 |
0x30 | 48 | SYBINT1 |  | no | 0 |
0x32 | 50 | SYBBIT |  | no | 0 |
0x34 | 52 | SYBINT2 |  | no | 0 |
0x38 | 56 | SYBINT4 |  | no | 0 |
0x3A | 58 | SYBDATETIME4 |  | no | 0 |
0x3B | 59 | SYBREAL |  | no | 0 |
0x3C | 60 | SYBMONEY |  | no | 0 |
0x3D | 61 | SYBDATETIME |  | no | 0 |
0x3E | 62 | SYBFLT8 |  | no | 0 |
0x40 | 64 | SYBSINT1 | 5 | no | 0 |
0x41 | 65 | SYBUINT2 | 5 | no | 0 |
0x42 | 66 | SYBUINT4 | 5 | no | 0 |
0x43 | 67 | SYBUINT8 | 5 | no | 0 |
0x62 | 98 | SYBVARIANT | 7+ | yes | 4 |
0x63 | 99 | SYBNTEXT | 7+ | yes | 4 | yes
0x67 | 103 | SYBNVARCHAR | 7+ | yes | 1 |
0x68 | 104 | SYBBITN |  | yes | 1 |
0x6A | 106 | SYBDECIMAL |  | yes | 1 |
0x6C | 108 | SYBNUMERIC |  | yes | 1 |
0x6D | 109 | SYBFLTN |  | yes | 1 |
0x6E | 110 | SYBMONEYN |  | yes | 1 |
0x6F | 111 | SYBDATETIMN |  | yes | 1 |
0x7A | 122 | SYBMONEY4 |  | no | 0 |
0x7F | 127 | SYBINT8 |  | no | 0 |
0xA5 | 165 | XSYBVARBINARY | 7+ | yes | 2 * |
0xA7 | 167 | XSYBVARCHAR | 7+ | yes | 2 * | yes
0xAD | 173 | XSYBBINARY | 7+ | yes | 2 |
0xAF | 175 | XSYBCHAR | 7+ | yes | 2 | yes
0xE1 | 225 | SYBLONGBINARY | 5 | yes | 4 |
0xE7 | 231 | XSYBNVARCHAR | 7+ | yes | 2 * | yes
0xEF | 239 | XSYBNCHAR | 7+ | yes | 2 | yes

* Under TDS 7.2+ these types allow size to be -1, representing varchar(max), varbinary(max) and nvarchar(max). Data representation for them changes:

- size is 64 (not 16) bits
- size of -1 means NULL
- size of -2 means the size is unknown
- the data are split in chunks, where each chunk starts with a 32-bit size
- a chunk with size <= 0 is the terminal chunk

## Collation type - TDS 7.1

The collation structure contains information about the character set encoding and comparison method.

     INT16      INT16    INT8
    +----------+--------+------------+
    | codepage | flags  | charset_id |
    +----------+--------+------------+

    codepage    windows codepage (see http://www.microsoft.com/globaldev/nlsweb/)
                also specified in lcid column of master..syslanguages
    flags       sort flags
                0x100 binary compare
                0x080 width insensitive
                0x040 Katatype insensitive
                0x020 accent insensitive
                0x010 case insensitive
                If binary flag is specified other flags are not present
                Low nibble of flags is a charset specifier (like chinese dialect)
    charset_id  charset id in master..syscharsets table or zero for no SQL collations

Collations names can be obtained from `select name from ::fn_helpcollations()` query

## Column Metadata

     INT8          XCHAR[n]       INT8    INT32   INT8
    +-------------+--------------+-------+-------+---------+
    | column name | column name  | flags |  user | column  |
    |   length    |              |       |  type |  type   |
    +-------------+--------------+-------+-------+---------+

     varies        INT8       INT8       INT16      XCHAR[n]     INT8     varies
    +-------------+----------+----------+----------+------------+--------+--------+
    | column size |precision |  scale   | t length | table name | locale | locale |
    |             |          |          |          |            | length |  info  |
    | (optional)  |(optional)|(optional)|(optional)| (optional) | (opt)  | (opt)  |
    +-------------+----------+----------+----------+------------+--------+--------+

    column name length
    column name        column name in result set, not necessarily db column name
    flags              bit flags
                       0x1  hidden (TDS 5.0)
                       0x2  key
                       0x10 writable
                       0x20 can be NULL
                       0x40 identity
    user type          usertype column from syscolumns
    column type        column type
    column size        not present for fixed size columns
    precision          present only for SYBDECIMAL and SYBNUMERIC
    scale              present only for SYBDECIMAL and SYBNUMERIC
    t length           present only for SYBTEXT and SYBIMAGE, length of table name
    table name         present only for SYBTEXT and SYBIMAGE
    locale length      length of locale info (in bytes)
                       only for TDS 5.0 results (not for parameters)
    locale info        unknown
                       only for TDS 5.0 results (not for parameters)

## Client request

Normal tokens (contained in packets 0xF)

    TODO

Special packets

- 0x1 1 Language
- 0x3 3 RPC TDS 4.6+
- 0x7 7 BCP TDS 5.0+

## Language packet (0x1 1)

This sample packet contain just SQL commands. It's supported by all TDS version (although TDS 5.0 have others token with similar use)

      XCHAR[n]
    +---------+
    | string  |
    +---------+

    string   SQL text

## RPC packet (0x3 3)

Do not confuse an RPC packet with an RPC token. The RPC packet is supported by all version of TDS; the RPC token is supported only by TDS 5.0 (and has different format). This is the oldest (and the only one in mssql) way to call directly an RPC. Sybase also documents it, but as 0xE.

      INT16         XCHAR[n]   INT16
    +-------------+----------+-------+----------+
    | name length | rpc name | flags | params   |
    +-------------+----------+-------+----------+

    name length   length of RPC name in characters.
                  mssql2k+ support some core RPC using numbers
                  If a number is used instead of name name length is marked as -1
                  (null) and a INT16 is used for the name.
                    0x1  1  sp_cursor
                    0x2  2  sp_cursoropen
                    0x3  3  sp_cursorprepare
                    0x4  4  sp_cursorexecute
                    0x5  5  sp_cursorprepexec
                    0x6  6  sp_cursorunprepare
                    0x7  7  sp_cursorfetch
                    0x8  8  sp_cursoroption
                    0x9  9  sp_cursorclose
                    0xA  10 sp_executesql
                    0xB  11 sp_prepare
                    0xC  12 sp_execute ???
                    0xD  13 sp_prepexec
                    0xE  14 sp_prepexecrpc
                    0xF  15 sp_unprepare
                  sp_execute seems to have some problems, even MS ODBC use name
                  version instead of number.
    rpc name      name of RPC.
    flags         bit flags.
                   0x1 1 recompile procedure (TDS 7.0+/TDS 5.0)
                   0x2 2 no metadata (TDS 7.0+)
                         (I don't know meaning of "no metadata" -- freddy77)
    params        parameters. See below

Every parameter has the following structure

    +-----------+------+
    | data info | data |
    +-----------+------+
    data info    data information. See below
    data         data. See results for detail

#### Data info structure

      INT8          XCHAR[n]     INT8    INT32
    +-------------+------------+-------+--------------------+
    | name length | param name | flags | usertype (TDS 5.0) |
    +-------------+------------+-------+--------------------+
      INT8   varies  varies     INT8[5]         INT8
    +------+-------+----------+---------------+------------------+
    | type | size  | optional | collate       | locale           |
    |      | (opt) | (opt)    | info(TDS 7.1) | length (TDS 5.0) |
    +------+-------+----------+---------------+------------------+

    name length   parameter name length (0 if unused)
    param name    parameter name
    flags         bit Name           Meaning
                  0x1 TDS_RPC_OUTPUT output parameter
                  0x2 TDS_RPC_NODEF  output parameter has no default value.
                                     Valid only with TDS_RPC_OUTPUT.

    usertype      usertype
    type          param type
    size          see Results
    optional      see Results. Blobs DO NOT have
                  optional on input parameters (output blob parameters
                  are not supported by any version of TDS).
    collate info  only for type that want collate info and using TDS 7.1
    locale length locale information length. Usually 0 (if not locale
                  information follow, the structure is unknown)

## Chained RPCs

Under TDS 7.0+ is possible to chain multiple RPCs together. This is useful to limit packets and round-trips with server. RPCs can be chained using byte 0x80 (TDS 7.0/TDS 7.1) or 0xFF (TDS 7.2).

           INT8                     INT8
    +-----+------------------------+----------------+-----+
    | RPC | 0x80 (TDS 7.0/TDS 7.1) | 0xFF (TDS 7.2) | RPC | ...
    +-----+------------------------+----------------+-----+

## Bulk Copy packet (0x7 7)

This documents a TDS 5.0 packet. It might be true for others....

### BCP Packet Structure

     INT8       INT16          INT32
    +----------+-------------+--------------------+
    |  packet  | last packet |  packet            |
    | type = 7 |  indicator  |   size             |
    +----------+-------------+--------------------+

    		followed by N row buffers,
    		where N is computed by exhausting the packet size

### BCP Packet Row Buffer

     INT16          INT8       INT8	      INT16
    +--------------+----------+----------+--------------+
    | size         |  ncols   |  zero    | size (again) |
    +--------------+----------+----------+--------------+

    	followed by column buffers (data), where

    		first, the fixed-size datatype columns

    		 fixed size and count (determined by column definition)
    		+--------------+
    		|    data .... | [repeats once for each mandatory column]
    		+--------------+

    		then, the variable-size (including nullable) datatype columns

    		 variable size and count
    		+--------------+
    		|    data .... | [repeats ncol times]
    		+--------------+

    		followed by two tables (!) to describe the column buffers

     Adjustment Table (optional)

     INT8       INT8
    +----------+----------+
    | 1 + ncols| offset   | [repeats ncol + 1 times]
    +----------+----------+

     Offset Table (mandatory)

     INT8       INT8
    +----------+----------+
    | 1 + ncols| offset   | [repeats ncol + 1 times]
    +----------+----------+

The BCP packet has a slightly different Packet header!?

### Computation of Offset and Adjustment tables

The offset and adjustment tables describe the postion of the first byte of each variable-size column. The first element holds the count of elements in the offset/adjustment table. Thereafer, the offsets are arranged in reverse order: the last element — which is also the last byte of the row buffer — holds the offset from the start of the row of the first variable-size column. The next-to-last offset table element holds the starting position of the second variable-size column, and so on.

#### Offset Table Example

1. 5
2. 31
3. 22
4. 21
5. 8
6. 4

The first element is 5 because there are five elements in the list. There are 4 column data buffers with 5 endpoints. The first column's data begins at offset 4. Computations:

column 1
  offset 4
  length: 4 = 8 - 4
column 2
  offset 8
  length: 13 = 21 - 8
column 3
  offset 21
  length: 1 = 22 - 21
column 4
  offset 22
  length: 9 = 31 - 22

Any column not accounted for is implicitly NULL. To represent a NULL column between two dataful columns, the offset table will have adjacent entries of the same value.

#### Adjustment table

The so-called adjustment table provides for longer rows. The reader will note the Offset table has 8-bit elements, which would limit the width of the table: the last variable column would have to end less than 256 bytes from the start fo the row. Rather than changing the definition of the Offset table, a second table, the Adjustment table, was introduced. It holds high-order bytes for the column offsets.

In other words, to compute a variable column's offset from the start of the row buffer, the server looks up its offset table value, then consults the same position in the adjustment table, and splices them together.

### Offset table commentary

The BCP packet is very dense. The data formats are governed by the table definition. Non-NULL columns of course must be present; there is no need to count them or compute their size. The NULL columns are undelimited; their boundaries are defined by the minimalist offset table.

The Adjustment table seems silly at first glance. Why not just make the offset table's elements 16 or or even 32 bits? The reason is overhead. Most rows will have less than 256 bytes of variable column data. By using the adjustment table, the BCP packet avoids adding one or even three empty bytes per column per row.

Why is the table in reverse order? Because that places the first offset at a known location: the end of each row gives the start of the first column. The server can work its way down the offset table and compute the column sizes. If they don't add up — if there are data between the (presumed) end of the last column and the start of the offset table — the server knows it should look for an adjustment table. Because the scheme is infinitely repeatable, rows could one day grow to terabyte widths without redefining the packet structure.

## Server Responses

Responses from the server start with a single octet (token) identifying its type. If variable length, they generally have the length as the second and third bytes

Tokens encountered thus far:

HEX | DEC | name | note
--- | --- | --- | ---
0x20 | 32 | Param Format 2 | 5.0 only
0x21 | 33 | Language | 5.0 only, client-side
0x22 | 34 | OrderBy 2 | 5.0 only??
0x61 | 97 | Row Format 2 | 5.0 only
0x71 | 113 | "Logout" | 5.0? ct_close(), client-side?
0x79 | 121 | Return Status |
0x7C | 124 | Process ID | 4.2 only
0x80 | 128 | Cursor Close | 5.0 only
0x81 | 129 | Cursor Delete | 5.0 only
0x81 | 129 | 7.0 Result | 7.0 only
0x82 | 130 | Cursor Fetch | 5.0 only
0x83 | 131 | Cursor Info | 5.0 only
0x84 | 132 | Cursor Open | 5.0 only
0x86 | 134 | Cursor Declare | 5.0 only
0x88 | 136 | 7.0 Compute Result | 7.0 only
0xA0 | 160 | Column Name | 4.2 only
0xA1 | 161 | Column Format | 4.2 only
0xA3 | 163 | Dynamic 2 | 5.0 only
0xA4 | 164 | Table names | name of tables in a FOR BROWSE select
0xA5 | 165 | Column Info | column information in a FOR BROWSE select
0xA6 | 166 | Option Cmd | 5.0 only
0xA7 | 167 | Compute Names |
0xA8 | 168 | Compute Result |
0xA9 | 169 | Order By |
0xAA | 170 | Error Message |
0xAB | 171 | Info Message |
0xAC | 172 | Output Parameters |
0xAD | 173 | Login Acknowledgement |
0xAE | 174 | Control |
0xD1 | 209 | Data --- Row Result |
0xD3 | 211 | Data --- Compute Result |
0xD7 | 215 | Params | 5.0 only
0xE2 | 226 | Capability | 5.0 only. Information on server
0xE3 | 227 | Environment Change | (database change, packet size, etc...)
0xE5 | 229 | Extended Error Message |
0xE6 | 230 | DBRPC | 5.0 only RPC calls
0xE7 | 231 | Dynamic | 5.0 only
0xEC | 236 | Param Format | 5.0 only
0xED | 237 | Authentication | 7.0 only
0xEE | 238 | Result Set | 5.0 only
0xFD | 253 | Result Set Done |
0xFE | 254 | Process Done |
0xFF | 255 | Done inside Process |

## Param Format 2 - TDS 5.0 (0x20 32)

TODO.

## Language - TDS 5.0 (0x21 33)

     INT32    INT8     CHAR[n]
    +--------+--------+-------+
    | length | status | query |
    +--------+--------+-------+

    length  total token length
    status  0 no args
            1 has args (followed by PARAMFMT/PARAMS)
    query   query (total length - 1)

## Order By 2 (0x22 34)

TODO.

## Row Format 2 - TDS 5.0 (0x61 97)

TODO.

## "Logout" (0x71 113)

No information. (1 byte, value=0 ?)

## Return Status (0x79 121)

     INT32
    +---------------+
    | Return status |
    +---------------+

The return value of a stored procedure.

## Process ID (0x7C 124)

     8 bytes
    +----------------+
    | process number |
    +----------------+

Presumably the process ID number for an executing stored procedure. (I'm not sure how this would ever be used by a client. *mjs*)

## Cursor Close - TDS 5.0 (0x80 128)

TODO.

## Cursor Delete - TDS 5.0 (0x81 129)

TODO.

## Result - TDS 7.0+ (0x81 129)

     INT16
    +----------+-------------+
    | #columns | column_info |
    +----------+-------------+

The TDS 7.0 column_info is formatted as follows for each column:

     INT16      INT16   INT8   varies  varies     INT8[5]         INT8          UCS2LE[n]
    +----------+-------+------+-------+----------+---------------+-------------+---------+
    | usertype | flags | type | size  | optional | collate       | name length | name    |
    |          |       |      | (opt) | (opt)    | info(TDS 7.1) |             |         |
    +----------+-------+------+-------+----------+---------------+-------------+---------+

    usertype	type modifier
    flags		bit flags
    		0x1  can be NULL
    		0x8  can be written (it's not an expression)
    		0x10 identity
    type		data type, values >128 indicate a large type
    size		none for fixed size types
    		4 bytes for blob and text
    		2 bytes for large types
    		1 byte for all others
    optional
                                   INT8        INT8
                                  +-----------+-------+
      numeric/decimal types:      | precision | scale |
                                  +-----------+-------+

                                   INT16               UCS2LE[n]
                                  +-------------------+------------+
      blob/text types:            | table name length | table name |
                                  +-------------------+------------+

      collate info are available only using TDS 7.1 and for characters types (but not
      for old type like short VARCHAR, only 2byte length versions)

## Cursor Fetch - TDS 5.0 (0x82 130)

TODO.

## Cursor Info - TDS 5.0 (0x83 131)

TODO.

## Cursor Open - TDS 5.0 (0x84 132)

TODO.

## Cursor Declare - TDS 5.0 (0x86 134)

TODO.

## Compute Result - TDS 7.0+ (0x88 136)

TODO.

## Column Name (0xA0 160)

     INT16          INT8      CHAR[n]               INT8      CHAR[n]
    +--------------+---------+--------------+------+---------+--------------+
    | total length | length1 | column1 name | .... | lengthN | columnN name |
    +--------------+---------+--------------+------+---------+--------------+

This token is the first token that contain result informations. Is usually followed by Column Format token (0xA1 161)

## Column Format (0xA1 161)

     INT16
    +--------------+-------------+
    | total length | column_info |
    +--------------+-------------+

The number of columns is the same of previous Column Name token.

The TDS 4.2 column_info is formatted as follows for each column:

     INT8[4]     INT8   varies  varies
    +-----------+------+-------+----------+
    | usertype/ | type | size  | optional |
    |   flags   |      | (opt) | (opt)    |
    +-----------+------+-------+----------+

    usertype/flags for Sybase

       INT32
      +----------+
      | usertype |
      +----------+

    usertype/flags for MSSQL

       INT16
      +----------+-------+
      | usertype | flags |
      +----------+-------+

    usertype	type modifier
    flags		bit flags (only MSSQL)
    		0x1  can be NULL
    		0x8  can be written (it's not an expression)
    		0x10 identity
    type		data type
    size		none for fixed size types
    		4 bytes for blob and text
    		1 byte for all others
                    (TDS 4.2 do not support large types)
    optional
                                   INT8        INT8
                                  +-----------+-------+
      numeric/decimal types:      | precision | scale |
      (supported??)               +-----------+-------+

                                   INT16               CHAR[n]
                                  +-------------------+------------+
      blob/text types:            | table name length | table name |
                                  +-------------------+------------+

## Dynamic 2 - TDS 5.0 (0xA3 163)

TODO.

## Option Cmd - TDS 5.0 (0xA6 166)

TODO.

## Compute Result (0xA8 168)

     INT16          INT16        INT8       varies        INT8      INT8[n]
    +--------------+------------+----------+-------------+---------+-------+
    | total length | compute id | #columns | column info | #bycols | bycol |
    +--------------+------------+----------+-------------+---------+-------+

column info:

     INT8       INT8      INT32      INT8     varies  INT8               varies
    +----------+---------+----------+--------+-------+------------------+----------------+
    | operator | operand | usertype | column | size  | locale length    | locale info    |
    |          |         |          |  type  | (opt) |  info (TDS 5.0)  | (TDS 5.0)      |
    +----------+---------+----------+--------+-------+------------------+----------------+

    operator      operator
                  0x4b COUNT
                  0x4c UNSIGNED? COUNT
                  0x4d SUM
                  0x4e UNSIGNED? SUM
                  0x4f AVG
                  0x50 UNSIGNED? AVG
                  0x51 MIN
                  0x52 MAX
                  0x09 COUNT_BIG (mssql2k)
                  0x30 STDEV (mssql2k)
                  0x31 STDEVP (mssql2k)
                  0x32 VAR (mssql2k)
                  0x33 VARP (mssql2k)
                  0x72 CHECKSUM_AGG (mssql2k)
    operand       ???
    usertype      usertype
    column type   data type
    size          data size
    locale length length of locale informations
    locale info   locale informations (unknown)

Each bycol information contains column info for a specific column.

TODO: optional possible?? collate infos ??

## TabName (0xA4 164)

TDS4/5/7:

     INT16          INT16         XCHAR[n]
    +--------------+-------------+------------+
    | total length | name length | table name | ...
    +--------------+-------------+------------+

    name length   table name length
    table name    table name

TDS 7.1:

     INT16          varies
    +--------------+-------------+
    | total length | table names |
    +--------------+-------------+

    table name:
     INT8              INT16              XCHAR[n]
    +-----------------+------------------+----------------+
    | # of components | component length | component name |
    +-----------------+------------------+----------------+

    ie:
      name        -> 01  04 00  ucs2le "name"
      db..name    -> 03  02 00  ucs2le "db"  00 00  04 00  ucs2le "name"
      db.dbo.name -> 03  02 00  ucs2le "db"  03 00  ucs2le "dbo"  04 00  ucs2le "name"

## Column Info (0xA5 165)

     INT16          varies
    +--------------+--------------+
    | total length | column infos |
    +--------------+--------------+

column info:

     INT8    INT8          INT8    INT8          XCHAR[n]
    +-------+-------------+-------+-------------+-------------+
    | index | table index | flags | name length | column name |
    |       |             |       |  (opt)      |  (opt)      |
    +-------+-------------+-------+-------------+-------------+

    index        index in result format (1-based)
    table index  index in previous TabName (1-based)
                 0 means no table (ie computed)
    flags        set of flags
                 0x04 expression
                 0x08 key
                 0x10 hidden
                 0x20 column name present
    name length  length of following column
    column name  real column name (result contain the label)

This token follow TabName token

## compute "control" ? (0xA7 167)

## "control" (0xAE 174)

Miscellaneous note (from *bdw* ?) found with 0xAE:

      has one byte for each column,
      comes between result(238) and first row(209),
      I believe computed column info is stored here, need to investigate

## Order By (0xA9 169)

     INT16    variable (1 byte per col)
    +--------+---------+
    | length | orders  |
    +--------+---------+

    length		Length of packet(and number of cols)
    orders          one byte per order by indicating the
                    column # in the output matching the
                    order from Column Info and Column Names
                    and data in following Row Data items.
                    A 0 indicates the column is not in the
                    resulting rows.

    an example:
    select first_name, last_name, number from employee
    order by salary, number
    assuming the columns are returned in the order
    queried:
    first_name then last_name, then number. we would have:
    ----------------
    |  2   | 0 | 3 |
    ----------------
    where length = 2 then the orders evaluate:
    0 for salary, meaning there is no salary data returned
    3 for number, meaning the 3rd data item corresponding
    to a column is the number

## Error Message (0xAA 170)

## Non-error Message (0xAB 171)

## Extended Error Message (0xE5 229)

     INT16    INT32        INT8    INT8
    +--------+------------+-------+-------+
    | length | msg number | state | level |
    +--------+------------+-------+-------+

     INT16      XCHAR[n]  INT8       XCHAR[n]  INT8       XCHAR[n]  INT16             INT32
    +----------+---------+----------+---------+----------+---------+-----------------+-----------------+
    | m length | message | s length | server  | p length | process | line#(TDS 7.1-) | line# (TDS 7.2) |
    +----------+---------+----------+---------+----------+---------+-----------------+-----------------+

    length		Length of packet
    msg number	SQL message number
    state		?
    level		An error if level > 10, a message if level <= 10
    m length	Length of message
    message		Text of error/message
    s length	Length of server name
    server		Name of "server" ?
    p length	Length of process name
    process name	Stored procedure name, if any
    line#		Line number of input which generated the message

## Output Parameters (0xAC 172)

Output parameters of a stored procedure.

     INT16    INT8       XCHAR[n]  INT8    INT32      INT8
    +--------+----------+---------+-------+----------+----------+------+
    | length | c length | colname | flags | usertype | datatype | .... |
    +--------+----------+---------+-------+----------+----------+------+

    length		Length of packet
    c length	Length of colname
    colname		Name of column
    flags		0x1 Nullable
    usertype	cf. systypes table in database
    datatype	Type of data returned

    The trailing information depends on whether the datatype is
    a fixed size datatype.
    				 N bytes
    				+---------+
      Datatype of fixed size N	| data    |
    				+---------+

    				 INT8          INT8            N bytes
    				+-------------+---------------+--------+
      Otherwise			| column size | actual size N | data   |
    				+-------------+---------------+--------+

## Login Acknowledgement (0xAD 173)

     INT16    INT8    4 bytes   INT8       XCHAR[n] 4 bytes
    +--------+-------+---------+----------+--------+----------+
    | length |  ack  | version | t length |  text  | ser_ver  |
    +--------+-------+---------+----------+--------+----------+

    length		length of packet
    ack		0x01 success	4.2
    		0x05 success	5.0
    		0x06 failure	5.0
    version		TDS version 4 bytes:  major.minor.?.?
    t length	length of text
    text		server name (ie 'Microsoft SQL Server')
    ser_ver		Server version
    		(with strange encoding, differring from TDS version)

## Data - Row Result (0xD1 209)

## Data - Compute Result (0xD3 211)

     INT8       variable size
    +----------+--------------------+
    |  token   |   row data         |
    +----------+--------------------+

Row data starts with one byte (decimal 209), for variable length types, a one byte length field precedes the data, for fixed length records just the data appears.
Note: nullable integers and floats are variable length.

For example: sp_who

The first field is spid, a smallint
The second field is status a char(12), in our example "recv sleep "

The row would look like this:

      byte  0 is the token
      bytes 1-2 are a smallint in low-endian
      byte  3 is the length of the char field
      bytes 4-15 is the char field

    byte  0   1   2   3   4   5   6   7   8   9  10  11  12  13  14  15
    hex  D1  01  00  0C  72  65  63  76  20  73  6C  65  65  70  20  20
        209   1   0  12   r   e   c   v ' '   s   l   e   e   p ' ' ' '

## Params - TDS 5.0 (0xD7 215)

TODO.

## Capability - TDS 5.0 (0xE2 226)

     INT16    variable
    +--------+--------------+
    | length | capabilities |
    +--------+--------------+

    length		Length of capability string
    capabilities	Server capabilities?  Related to login magic?

## Environment change (0xE3 227)

     INT16    INT8       INT8        CHAR[n]   INT8        CHAR[n]
    +--------+----------+-----------+---------+-----------+---------+
    | length | env code | t1 length |  text1  | t2 length |  text2  |
    +--------+----------+-----------+---------+-----------+---------+

    env code	Code for what part of environment changed
    	0x01  database context
    	0x02  language
    	0x03  character set
    	0x04  packet size
    	0x05  TDS 7.0+ LCID
    	0x06  TDS 7.0+ ??? (sort method? sql server encoding?)
    	0x07  Collation info
    text1		Old value
    text2		New value

    text1 and text2 are text information (coded in ucs2 in TDS 7.0+) except
    collation info that's a structure (see collation structure)

## DBRPC - TDS 5.0 (0xE6 230)

TODO.

## Dynamic - TDS 5.0 (0xE7 231)

TODO.

## Param Format - TDS 5.0 (0xEC 236)

     INT16     INT16        variable size
    +---------+------------+-------------------+
    | length  | number of  | parameter info    |
    |         | parameters |                   |
    +---------+------------+-------------------+

    length            	length of message following this field
    number of parameters	number of parameter formats following
    list of formats		I (*bdw*) imagine it uses the column format structure.

## Authentication - TDS 7.0 (0xED 237)

     INT16     varies
    +---------+------+
    | length  | auth |
    +---------+------+

    length   length of authentication data following this field
    auth     authentication data
             for NTLM this is message 2

Client reply with Authentication packet.

## Result Set - TDS 5.0 (0xEE 238)

     INT16     INT16        variable size
    +---------+------------+-----------------+
    | length  | number of  | column info     |
    |         | columns    |                 |
    +---------+------------+-----------------+

    Fields:
    length             length of message following this field
    number of columns  number of columns in the result set, this many column
                       information fields will follow.
    column info        column info

## Done Packets

Result Set Done (0xFD 253)
Process Done (0xFE 254)
Done Inside Process (0xFF 255)

     INT16       INT16     INT32                  INT64
    +-----------+---------+----------------------+---------------------+
    | bit flags | unknown | row count (TDS 7.1-) | row count (TDS 7.2) |
    +-----------+---------+----------------------+---------------------+

    Fields:
    bit flags          0x01 more results
    		   0x02 error (like invalid sql syntax)
    		   0x10 row count is valid
    		   0x20 cancelled
    unknown            2,0  /* something to do with block size perhaps */
    row count          number of rows affected / returned in the result set.
                       row count is 64-bit using TDS 7.2.
    		(FIXME check if "affected / returned" is correct)

"Result Set Complete" is the end of a query that doesn't create a process on the server. I.e., it doesn't call a stored procedure.
"Process Done" is the end of a stored procedure
"Done In Process" means that a query internal to a stored procedure has finished, but the stored procedure isn't done overall.

## Acknowledgements

The following people have contributed to this document:

- Brian Bruns (first draft, protocol discovery)
- Brian Wheeler (protocol discovery)
- Mark Schaal (second draft)
- Frediano Ziglio

(short list)

## Document Status

$Id: tds.html,v 1.41 2008-11-25 23:38:33 jklowden Exp $