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SQLSpecialColumns
SQLSpecialColumns
•
SQLSpecialColumns retrieves the following information about columns within a specified table:
The optimal set of columns that uniquely identifies a row in the table.
• Columns that are automatically updated when any value in the row is updated by a transaction.
SQLSpecialColumnsW() as a Unicode string supports same execution as SQLSpecialColumns().
Syntax
SQLRETURN SQLSpecialColumns (
SQLHSTMT stmt,
SQLSMALLINT fColType,
SQLCHAR *szTableQual,
SQLSMALLINT cbTableQual,
SQLCHAR *szTableOwner,
SQLSMALLINT cbTableOwner,
SQLCHAR *szTableName,
SQLSMALLINT cbTableName,
SQLSMALLINT fScope,
SQLSMALLINT fNullable );
Arguments
Data Type
SQLHSTMT
SQLSMALLINT
Argument stmt fColType
In/Out
Input
Input
SQLCHAR *
SQLSMALLINT
SQLCHAR *
SQLSMALLINT
SQLCHAR *
SQLSMALLINT
SQLSMALLINT szTableQual cbTableQual szTableName cbTableName fScope
Input
Input szTableOwner Input cbTable-
Owner
Input
Input
Input
Input
Description
Statement handle
Type of the column to be returned
SQL_BEST_ROWID: Returns the optimal column that uniquely identify the rows in the table by searching column value(s).
Null will be always returned.
The character number of * szTableQual
Schema Name
The character number of *szTableOwner’
The table name. Cannot be a NULL pointer.
The character number of *szTableNam
Not used
ODBC Users’ Manual 158
Data Type
SQLSMALLINT
Argument fNullable
In/Out
Input
SQLSpecialColumns
Description
Not used (Does not allow NULL data because the corresponding columns are returned to the primary keys.)
Return Values
SQL_SUCCESS
SQL_SUCCESS_WITH_INFO
SQL_INVALID_HANDLE
SQL_ERROR
Description
When fColType is SQL_BEST_ROWID, SQLSpecialColumns () returns column(s) that uniquely identify each row in the table. These columns can be used in select-list or Where clause.
SQLSpecialColumns () is used to return these columns because SQLColumns () does not return the columns that are automatically updated when columns or rows are updated by the transaction.
If there are no columns that uniquely identifies each row in the table, SQLSpecialColumns () will return the row set without rows. To subsequently call SQLFetch () on the command syntax, return
SQL_NO_DATA.
When the fact that the database does not support fColType, fScope, and fNullable arguments is stated, SQLSpecialColumns () will return the empty result set.
Columns Returned by SQLSpecialColumns ()
Name
SCOPE 1
COLUMN_NAME 2
No.
DATA_TYPE
TYPE_NAME
COLUMN_SIZE
3
4
5
Data Type
SMALLINT
VARCHAR
(NOT NULL)
SMALLINT
(NOT NULL)
VARCHAR
(NOT NULL)
INTEGER
Description
SQL_SCOPE_SESSION value is fixed to 2.
Column Name.As for the unnamed string, ODBC returns the empty character string.
SQL data type
Character string representing the name of the data type corresponding to DATA_TYPE.
Column Size. NULL will be returned when the string size is not proper.
159 ODBC Functions
SQLSpecialColumns
Name
BUFFER_LENGTH 6
DECIMAL_DIGITS 7
No.
Data Type
INTEGER
SMALLINT
PSEUDO_COLUM
N
8 SMALLINT
Description
The maximum byte storing the data
The NULL will return the data type that cannot apply the decimal points of the column and the decimal points.
Maximum digits of the character of binary datatype string. For other data types, NULL will be returned.
Diagnosis
SQLSTATE
08S01
HY009
Description
Communication line failure
Use an invalid pointer (null pointer)
Comments
Communication channel failure before the function processing is completed between the ODBC and the database szTableName is a NULL pointer.
Related Functions
SQLBindCol
SQLColumns
SQLFetch
SQLPrimaryKeys
Example
See: $ALTIBASE_HOME/sample/SQLCLI/demo_meta7.cpp .> if (SQLSpecialColumns(stmt, 0,
NULL, 0,
NULL, 0,
"DEMO_META7", SQL_NTS,
NULL, 0) != SQL_SUCCESS)
{
execute_err(dbc, stmt, "SQLColumns");
SQLFreeStmt(stmt, SQL_DROP);
return SQL_ERROR;
}
SQLBindCol(stmt, 2, SQL_C_CHAR, szColumnName, STR_LEN, &cbColumnName);
SQLBindCol(stmt, 3, SQL_C_SSHORT, &DataType, 0, &cbDataType);
SQLBindCol(stmt, 4, SQL_C_CHAR, szTypeName, STR_LEN, &cbTypeName);
ODBC Users’ Manual 160
SQLSpecialColumns
SQLBindCol(stmt, 5, SQL_C_SLONG, &ColumnSize, 0, &cbColumnSize);
SQLBindCol(stmt, 6, SQL_C_SLONG, &BufferLength, 0, &cbBufferLength);
SQLBindCol(stmt, 7, SQL_C_SSHORT, &DecimalDigits, 0, &cbDecimalDigits);
161 ODBC Functions
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