MDAC 2.5 SDK - ODBC Programmer's Reference
Chapter 21: ODBC API Reference


 

SQLNumResultCols

Conformance

Version Introduced: ODBC 1.0
Standards Compliance: ISO 92

Summary

SQLNumResultCols returns the number of columns in a result set.

Syntax

SQLRETURN SQLNumResultCols(
     SQLHSTMT     StatementHandle,
     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