Managing & Using MySQL, 2nd Edition

Name

mysql_store_result —

Synopsis

MYSQL_RES *mysql_store_result(MYSQL *mysql)

Reads the entire result of a query and stores it in a MYSQL_RES structure. Either this function or mysql_use_result must be called to access return information from a query. You must call mysql_free_result to free the MYSQL_RES structure when you are done with it.

The function returns a null value in the case of an error. The function also returns a null value if the query was not of a type that returns data (such as an INSERT or UPDATE query). If you receive a null pointer and are not sure if the query was supposed to return data or not, you can call mysql_field_count to find the number of fields the query was supposed to return. If zero, then it was a non-SELECT statement, and the pointer should be null. Otherwise, an error has occurred.

If the query was a SELECT-type statement, but happens to contain no data, this function will still return a valid (but empty) MYSQL_RES structure (it will not be a null pointer).

Example

MYSQL_RES results; mysql_query(&mysql, "SELECT * FROM people"); results = mysql_store_result(&mysql); /* 'results' should now contain all of the information from the 'people' table */ if (!results) { printf("An error has occurred!\n"); } /* 'query' is some query string we obtained elsewhere, we're not sure what it is... */ mysql_query(&mysql, query); results = mysql_store_result(&mysql); if (!results) { /* An error might have occurred, or maybe this is just a non-SELECT statement */ ...