2.2.7.1 ALTMETADATA
Token Stream Name:
-
ALTMETADATA
Token Stream Function:
Describes the data type, length, and name of column data that result from a SQL statement that generates totals.
Token Stream Comments:
The token value is 0x88.
This token is used to tell the client the data type and length of the column data. It describes the format of the data found in an ALTROW data stream. ALTMETADATA and the corresponding ALTROW MUST be in the same result set.
All ALTMETADATA data streams are grouped.
A preceding COLMETADATA (section 2.2.7.4) MUST exist before an ALTMETADATA token. There might be COLINFO and TABNAME streams between COLMETADATA and ALTMETADATA.
Note ALTMETADATA was deprecated in TDS 7.4.
Token Stream-Specific Rules:
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TokenType = BYTE Count = USHORT Id = USHORT ByCols = UCHAR Op = BYTE Operand = USHORT UserType = USHORT/ULONG; (changed to ULONG in TDS 7.2) fNullable = BIT fCaseSen = BIT usUpdateable = 2BIT ; 0 = ReadOnly ; 1 = Read/Write ; 2 = Unused fIdentity = BIT fComputed = BIT ; (introduced in TDS 7.2) usReservedODBC = 2BIT fFixedLenCLRType = BIT ; (introduced in TDS 7.2) usReserved = 7BIT Flags = fNullable fCaseSen usUpdateable fIdentity (FRESERVEDBIT / fComputed) usReservedODBC (FRESERVEDBIT / fFixedLenCLRType) usReserved NumParts = BYTE ; (introduced in TDS 7.2) PartName = US_VARCHAR ; (introduced in TDS 7.2) TableName = US_VARCHAR ; (removed in TDS 7.2) / (NumParts 1*PartName) ; (introduced in TDS 7.2) ColName = B_VARCHAR ColNum = USHORT ComputeData = Op Operand UserType Flags TYPE_INFO [TableName] ColName
The TableName field is specified only if a text, ntext, or image column is included in the result set.
Token Stream Definition:
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ALTMETADATA = TokenType Count Id ByCols *(<ByCols> ColNum) 1*ComputeData
Token Stream Parameter Details:
|
Parameter |
Description |
|---|---|
|
TokenType |
ALTMETADATA_TOKEN<39> |
|
Count |
The count of columns (number of aggregate operators) in the token stream. |
|
Id |
The Id of the SQL statement to which the total column formats apply. Each ALTMETADATA token MUST have its own unique Id in the same result set. This Id lets the client correctly interpret later ALTROW data streams. |
|
ByCols |
The number of grouping columns in the SQL statement that generates totals. For example, the SQL clause compute count(sales) by year, month, division, department has four grouping columns. |
|
Op |
The type of aggregate operator.
|
|
Operand |
The column number, starting from 1, in the result set that is the operand to the aggregate operator. |
|
UserType |
The user type ID of the data type of the column. Depending on the TDS version that is used, valid values are 0x0000 or 0x00000000, with the exceptions of data type timestamp (0x0050 or 0x00000050) and alias types (greater than 0x00FF or 0x000000FF). |
|
Flags |
These bit flags are described in least significant bit order. With the exception of fNullable, all of these bit flags SHOULD be set to zero. For a description of each bit flag, see section 2.2.7.4:
|
|
TableName |
See section 2.2.7.4 for a description of TableName. This field SHOULD never be sent because SQL statements that generate totals exclude NTEXT/TEXT/IMAGE. |
|
ColName |
The column name. Contains the column name length and column name. |
|
ColNum |
USHORT specifying the column number as it appears in the COMPUTE clause. ColNum appears ByCols times. |