A typical MySQL C API program involves three steps in query processing:

  Query construction

Depending upon your requirement you can construct a null terminated 

string or counted length string for the query: 

c

har *query;

  Execute the query

For executing the query you can use 

mysql_real_query()

 for a counted 

length query string or 

mysql_query() 

for a null terminated query string. 

Example 7 47 shows the processing of a query with both 

mysql_real_query()

 and 

mysql_query() 

method calls.

  Processing of the returned results

After executing the query, the final step is to process the results. All the 

statements except select, show, describe, and explain do not return any 

results; optionally in those query mysql provides 

mysql_affected_rows() 

for accessing the number of rows effected. 

If your query returns a result set, follow these steps for the result 

processing:

i. Generate the result set using 

mysql_store_result()

 or 

mysql_use_result()

.

ii. Fetch each row using 

mysql_fetch_row()

iii. Deallocate the result set using 

mysql_free_result()

Example 7 47shows an example for both MySQL query, which returns results 

as well as querys that do not return results.

Example 7 47   MySQL query processing

MYSQL_RES *result;

if (mysql_query(conn, "SELECT wk_id, user_id,status FROM warenkorb") != 0){

/* handle error */

return 1;

}

else

{

result = mysql_store_result (conn); /* generate result set */

if (result == NULL){

/* handle error */

return 1;

}else

{

/* process result set, then deallocate it */

MYSQL_ROW row;

MYSQL_FIELD* fd ;

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MySQL to DB2 UDB Conversion Guide