OpenDBX/C API/odbx result
#include <odbx.h>
int odbx_result(
odbx_t* handle,
odbx_result_t** result,
struct timeval* timeout,
unsigned long chunk )
Description
Retrieves the result of a query statement sent by odbx_query() from the database server. After a statement was successfully executed, a dynamically allocated object representing the result set is stored in result which must be freed afterwards by odbx_result_free(). Result sets for SELECT-like statements returned successfully by this function can be processed by calling odbx_row_fetch() until all rows are retrieved. If the statement was an INSERT, UPDATE, DELETE or a similar statement, the number of affected rows are available via odbx_rows_affected.
If a timeout or error occurs, the result pointer is set to NULL. In case of a timeout, odbx_result() should be called again because the query isn't canceled. This function must be called multiple times until it returns zero, even if the query contains only one statement. Otherwise, memory will be leaked and odbx_query() will return an error until this is done.
The third parameter restricts the time the function is waiting for a result form the server. It may be NULL to wait until a result arrives. Otherwise, it can contain any number of seconds and microseconds in a timeval structure to wait for. The timeval structure must be set each time before calling odbx_result() because its content may be changed by the function. If the server doesn't respond within the timeout, the query isn't canceled! Instead, the next call to this function will wait for the same result set. Waiting the specified time may be implemented in the backends if it is possible, but there is no guarantee. If not, odbx_result() will return not before a responds arrives.
Dependent on the native database library, it may be possible to retrieve all results at once (if chunk is zero), one by one or more at once. All positive values including zero are allowed as values for chunk If paging (more at once) is not supported by the backend, it will use "one by one" or "all at once" if this is the only option provided.
Parameters:
- handle: Connection object created by odbx_init()
- result: Pointer to a result pointer
- timeout: Amount of time waiting for a result
- chunk: Number of rows to fetch at once
Return values:
- Three if a result is available
- Two if the query was not SELECT-like
- One in case of a timeout
- Zero if no more results are available
- Less than zero if an error occured
Errors:
- -ODBX_ERR_BACKEND: Any error returned by the backend
- -ODBX_ERR_PARAM: "handle" or "result" is NULL or "handle" is invalid
- -ODBX_ERR_NOMEM: Allocating new memory failed
- -ODBX_ERR_RESULT: Waiting of result failed
See also:
- OpenDBX_column_count
- OpenDBX_column_name
- OpenDBX_column_type
- OpenDBX_rows_affected
- OpenDBX_row_fetch
- OpenDBX_result_free
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