Prepared statements provide performance advantages for statements that are used repeatedly. ODBC provides a full set of functions for using prepared statements.
For an introduction to prepared statements, see Preparing statements.
To execute a prepared SQL statement
Prepare the statement using SQLPrepare.
For example, the following code fragment illustrates how to prepare an INSERT statement:
SQLRETURN retcode; SQLHSTMT stmt; retcode = SQLPrepare( stmt, "INSERT INTO Departments ( DepartmentID, DepartmentName, DepartmentHeadID ) VALUES (?, ?, ?,)", SQL_NTS);
In this example:
retcode Holds a return code that should be tested for success or failure of the operation.
stmt Provides a handle to the statement so that it can be referenced later.
? The question marks are placeholders for statement parameters.
Set statement parameter values using SQLBindParameter.
For example, the following function call sets the value of the DepartmentID variable:
SQLBindParameter( stmt, 1, SQL_PARAM_INPUT, SQL_C_SSHORT, SQL_INTEGER, 0, 0, &sDeptID, 0, &cbDeptID);
In this example:
stmt is the statement handle.
1 indicates that this call sets the value of the first placeholder.
SQL_PARAM_INPUT indicates that the parameter is an input statement.
SQL_C_SHORT indicates the C data type being used in the application.
SQL_INTEGER indicates SQL data type being used in the database.
The next two parameters indicate the column precision and the number of decimal digits: both zero for integers.
&sDeptID is a pointer to a buffer for the parameter value.
0 indicates the length of the buffer, in bytes.
&cbDeptID is a pointer to a buffer for the length of the parameter value.
Bind the other two parameters and assign values to sDeptId.
Execute the statement:
retcode = SQLExecute( stmt);
Steps 2 to 4 can be carried out multiple times.
Drop the statement.
Dropping the statement frees resources associated with the statement itself. You drop statements using SQLFreeHandle.
For a complete sample, including error checking, see samples-dir\SQLAnywhere\ODBCPrepare\odbcprepare.cpp.
For more information about SQLPrepare, see SQLPrepare in the Microsoft ODBC Programmer's Reference.
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