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2.2.3.1.1 Type

Type defines the type of message. Type is a 1-byte unsigned char. Types are as follows:

Value

Description

Buffer data?

1

SQL batch. This can be any language that the server understands.

Yes

2

Pre-TDS7 login (only used by legacy clients older than Microsoft SQL Server 7.0).

Yes

3

RPC.

Yes

4

Tabular result. This indicates a stream that contains the server response to a client request.

Yes

5

Unused.

-

6

Attention signal.

No

7

Bulk load data. This type is used to send binary data to the server.

Yes

8-13

Unused.

-

14

Transaction manager request.

Yes

15

Unused.

-

16

TDS7 login (MUST be used by all clients that support SQL Server 7.0 or later).

Yes

17

SSPI message.

Yes

18

Pre-login message.

Yes

If an unknown Type is specified, the message receiver SHOULD disconnect the connection. If a valid Type is specified, but is unexpected (per section 3), the message receiver SHOULD disconnect the connection. This applies to both the client and the server. For example, the server could disconnect the connection if the server receives a message with Type equal 16 when the connection is already logged in.

The following table highlights which messages, as described previously in sections 2.2.1 and 2.2.2, correspond to which packet header type.

Message type

Client or server message

Buffer header type

Pre-Login

Client

2 or 18 depending on whether the client supports TDS v7.0+

Login

Client

16 + 17 (if Integrated authentication)

SQL batch

Client

1

Bulk load

Client

7

RPC

Client

3

Attention

Client

6

Transaction Manager Request

Client

14

FeatureExtAck

Server

4

Pre-Login Response

Server

4

Login Response

Server

4

Row Data

Server

4

Return Status

Server

4

Return Parameters

Server

4

Response Completion ("DONE")

Server

4

Session State

Server

4

Error and Info Messages

Server

4

Attention Acknowledgement

Server

4

 
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