Conformance
Version Introduced:ODBC 1.0
Standards Compliance:ISO 92
Summary
SQLNumResultCols returns the number of columns in a result set.
Syntax
SQLRETURN SQLNumResultCols(
SQLHSTMTStatementHandle,
SQLSMALLINT *ColumnCountPtr);
Arguments
StatementHandle
[Input]
Statement handle.
ColumnCountPtr
[Output]
Pointer to a buffer in which to return the number of columns in the result set. This count does not include a bound bookmark column.
Returns
SQL_SUCCESS, SQL_SUCCESS_WITH_INFO, SQL_STILL_EXECUTING, SQL_ERROR, or SQL_INVALID_HANDLE.
Diagnostics
When SQLNumResultCols 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 commonly returned by SQLNumResultCols 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.) |
| 08S01 | Communication link failure | The communication link between the driver and the data source to which the driver was connected failed before the function completed processing. |
| 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. |
| HY008 | Operation canceled | Asynchronous processing was enabled for the StatementHandle. The function was called and, before it completed execution, SQLCancel was called on the StatementHandle; the function was then called again on the StatementHandle. The function was called and, before it completed execution, SQLCancel was called on the StatementHandle from a different thread in a multithread application. |
| HY010 | Function sequence error | (DM) The function was called prior to calling SQLPrepare or SQLExecDirect for the StatementHandle. (DM) An asynchronously executing function (not this one) 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. |
| 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. |
SQLNumResultCols can return any SQLSTATE that can be returned by SQLPrepare or SQLExecute when called after SQLPrepare and before SQLExecute, depending on when the data source evaluates the SQL statement associated with the statement.
Comments
SQLNumResultCols can be called successfully only when the statement is in the prepared, executed, or positioned state.
If the statement associated with StatementHandle does not return columns, SQLNumResultCols sets *ColumnCountPtr to 0.
The number of columns returned by SQLNumResultCols is the same value as the SQL_DESC_COUNT field of the IRD.
For more information, see “Was a Result Set Created?” and “How is Metadata Used?” in Chapter 10, “Retrieving Results (Basic).”
Related Functions
| For information about | See |
| Binding a buffer to a column in a result set | SQLBindCol |
| Canceling statement processing | SQLCancel |
| Returning information about a column in a result set | SQLColAttribute |
| Returning information about a column in a result set | SQLDescribeCol |
| Executing an SQL statement | SQLExecDirect |
| Executing a prepared SQL statement | SQLExecute |
| Fetching a block of data or scrolling through a result set | SQLFetchScroll |
| Fetching a single row or a block of data in a forward-only direction | SQLFetch |
| Fetching part or all of a column of data | SQLGetData |
| Preparing an SQL statement for execution | SQLPrepare |
| Setting cursor scrolling options | SQLSetStmtAttr |