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(mysql.info)mysql_use_result

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`mysql_use_result()'
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`MYSQL_RES *mysql_use_result(MYSQL *mysql)'

Description
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You must call `mysql_store_result()' or `mysql_use_result()' for every
query that successfully retrieves data (`SELECT', `SHOW', `DESCRIBE',
`EXPLAIN').

`mysql_use_result()' initiates a result set retrieval but does not
actually read the result set into the client like `mysql_store_result()'
does.  Instead, each row must be retrieved individually by making calls
to `mysql_fetch_row()'.  This reads the result of a query directly from
the server without storing it in a temporary table or local buffer,
which is somewhat faster and uses much less memory than
`mysql_store_result()'.  The client will only allocate memory for the
current row and a communication buffer that may grow up to
`max_allowed_packet' bytes.

On the other hand, you shouldn't use `mysql_use_result()' if you are
doing a lot of processing for each row on the client side, or if the
output is sent to a screen on which the user may type a `^S' (stop
scroll).  This will tie up the server and prevent other threads from
updating any tables from which the data is being fetched.

When using `mysql_use_result()', you must execute `mysql_fetch_row()'
until a `NULL' value is returned, otherwise the unfetched rows will be
returned as part of the result set for your next query. The C API will
give the error `Commands out of sync; You can't run this command now'
if you forget to do this!

You may not use `mysql_data_seek()', `mysql_row_seek()',
`mysql_row_tell()', `mysql_num_rows()', or `mysql_affected_rows()' with
a result returned from `mysql_use_result()', nor may you issue other
queries until the `mysql_use_result()' has finished.  (However, after
you have fetched all the rows, `mysql_num_rows()' will accurately
return the number of rows fetched.)

You must call `mysql_free_result()' once you are done with the result
set.

Return Values
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A `MYSQL_RES' result structure. `NULL' if an error occurred.

Errors
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`CR_COMMANDS_OUT_OF_SYNC'
     Commands were executed in an improper order.

`CR_OUT_OF_MEMORY'
     Out of memory.

`CR_SERVER_GONE_ERROR'
     The MySQL server has gone away.

`CR_SERVER_LOST'
     The connection to the server was lost during the query.

`CR_UNKNOWN_ERROR'
     An unknown error occurred.