SQLFreeStmt Function
Conformance
Version Introduced: ODBC 1.0 Standards Compliance: ISO 92
Summary
SQLFreeStmt stops processing associated with a specific statement, closes any open cursors associated with the statement, discards pending results, or, optionally, frees all resources associated with the statement handle.
Syntax
SQLRETURN SQLFreeStmt(
SQLHSTMT StatementHandle,
SQLUSMALLINT Option);
Arguments
StatementHandle
[Input] Statement handle
Option
[Input] One of the following options:
SQL_ CLOSE: Closes the cursor associated with StatementHandle (if one was defined) and discards all pending results. The application can reopen this cursor later by executing a SELECT statement again with the same or different parameter values. If no cursor is open, this option has no effect for the application. SQLCloseCursor can also be called to close a cursor. For more information, see Closing the Cursor.
SQL_DROP: This option is deprecated. A call to SQLFreeStmt with an Option of SQL_DROP is mapped in the Driver Manager to SQLFreeHandle.
SQL_UNBIND: Sets the SQL_DESC_COUNT field of the ARD to 0, releasing all column buffers bound by SQLBindCol for the given StatementHandle. This does not unbind the bookmark column; to do that, the SQL_DESC_DATA_PTR field of the ARD for the bookmark column is set to NULL. Notice that if this operation is performed on an explicitly allocated descriptor that is shared by more than one statement, the operation will affect the bindings of all statements that share the descriptor. For more information, see Overview of Retrieving Results (Basic).
SQL_RESET_PARAMS: Sets the SQL_DESC_COUNT field of the APD to 0, releasing all parameter buffers set by SQLBindParameter for the given StatementHandle. If this operation is performed on an explicitly allocated descriptor that is shared by more than one statement, this operation will affect the bindings of all the statements that share the descriptor. For more information, see Binding Parameters.
Returns
SQL_SUCCESS, SQL_SUCCESS_WITH_INFO, SQL_ERROR, or SQL_INVALID_HANDLE.
Diagnostics
When SQLFreeStmt returns SQL_ERROR or SQL_SUCCESS_WITH_INFO, an associated SQLSTATE value can be obtained by calling SQLGetDiagRec with a HandleType of SQL_HANDLE_STMT and a Handle of StatementHandle. The following table lists the SQLSTATE values typically returned by SQLFreeStmt and explains each one in the context of this function; the notation "(DM)" precedes the descriptions of SQLSTATEs returned by the Driver Manager. The return code associated with each SQLSTATE value is SQL_ERROR, unless noted otherwise.
| SQLSTATE | Error | Description |
|---|---|---|
| 01000 | General warning | Driver-specific informational message. (Function returns SQL_SUCCESS_WITH_INFO.) |
| HY000 | General error | An error occurred for which there was no specific SQLSTATE and for which no implementation-specific SQLSTATE was defined. The error message returned by SQLGetDiagRec in the *MessageText buffer describes the error and its cause. |
| HY001 | Memory allocation error | The driver was unable to allocate memory required to support execution or completion of the function. |
| HY010 | Function sequence error | (DM) An asynchronously executing function was called for the connection handle that is associated with the StatementHandle. This asynchronous function was still executing when SQLFreeStmt was called. (DM) SQLExecute, SQLExecDirect, or SQLMoreResults was called for the StatementHandle and returned SQL_PARAM_DATA_AVAILABLE. This function was called with Option set to SQL_RESET_PARAMS before data was retrieved for all streamed parameters. (DM) An asynchronously executing function was called for the StatementHandle and was still executing when this function was called. (DM) SQLExecute, SQLExecDirect, SQLBulkOperations, or SQLSetPos was called for the StatementHandle and returned SQL_NEED_DATA. This function was called before data was sent for all data-at-execution parameters or columns. |
| HY013 | Memory management error | The function call could not be processed because the underlying memory objects could not be accessed, possibly because of low memory conditions. |
| HY092 | Option type out of range | (DM) The value specified for the argument Option was not: SQL_CLOSE SQL_DROP SQL_UNBIND SQL_RESET_PARAMS |
| HYT01 | Connection timeout expired | The connection timeout period expired before the data source responded to the request. The connection timeout period is set through SQLSetConnectAttr, SQL_ATTR_CONNECTION_TIMEOUT. |
| IM001 | Driver does not support this function | (DM) The driver associated with the StatementHandle does not support the function. |
Comments
Calling SQLFreeStmt with the SQL_CLOSE option is equivalent to calling SQLCloseCursor, except that SQLFreeStmt with SQL_CLOSE does not affect the application if no cursor is open on the statement. If no cursor is open, a call to SQLCloseCursor returns SQLSTATE 24000 (Invalid cursor state).
An application should not use a statement handle after it has been freed; the Driver Manager does not check the validity of a handle in a function call.
Example
It is a good programming practice to free handles. However, for simplicity, the following sample does not include code that frees allocated handles. For an example of how to free handles, see SQLFreeHandle Function.
// SQLFreeStmt.cpp
// compile with: user32.lib odbc32.lib
#include <windows.h>
#include <sqlext.h>
int main() {
// declare and initialize the environment, connection, statement handles
SQLHENV henv = NULL; // Environment
SQLHDBC hdbc = NULL; // Connection handle
SQLHSTMT hstmt = NULL; // Statement handle
SQLRETURN retCode;
HWND desktopHandle = GetDesktopWindow(); // desktop's window handle
SQLCHAR connStrbuffer[1024];
SQLSMALLINT connStrBufferLen;
retCode = SQLAllocHandle(SQL_HANDLE_ENV, SQL_NULL_HANDLE, &henv);
retCode = SQLSetEnvAttr(henv, SQL_ATTR_ODBC_VERSION, (void*)SQL_OV_ODBC3, -1);
retCode = SQLAllocHandle(SQL_HANDLE_DBC, henv, &hdbc);
retCode = SQLSetConnectAttr(hdbc, SQL_LOGIN_TIMEOUT, (SQLPOINTER)10, 0);
retCode = SQLDriverConnect(hdbc, desktopHandle, (SQLCHAR *)"Driver={SQL Server}", SQL_NTS, connStrbuffer, 1024 + 1, &connStrBufferLen, SQL_DRIVER_PROMPT);
retCode = SQLAllocHandle(SQL_HANDLE_STMT, hdbc, &hstmt);
retCode = SQLFreeStmt(hstmt, SQL_CLOSE);
retCode = SQLFreeStmt(hstmt, SQL_UNBIND);
retCode = SQLFreeStmt(hstmt, SQL_RESET_PARAMS);
}
Related Functions
| For information about | See |
|---|---|
| Allocating a handle | SQLAllocHandle Function |
| Canceling statement processing | SQLCancel Function |
| Closing a cursor | SQLCloseCursor Function |
| Freeing a handle | SQLFreeHandle Function |
| Setting a cursor name | SQLSetCursorName Function |