- 20.9.3 C API Function Descriptions
- 20.9.3.1 mysql_affected_rows()
- 20.9.3.2 mysql_autocommit()
- 20.9.3.3 mysql_change_user()
- 20.9.3.4 mysql_character_set_name()
- 20.9.3.5 mysql_close()
- 20.9.3.6 mysql_commit()
- 20.9.3.7 mysql_connect()
- 20.9.3.8 mysql_create_db()
- 20.9.3.9 mysql_data_seek()
- 20.9.3.10 mysql_debug()
- 20.9.3.11 mysql_drop_db()
- 20.9.3.12 mysql_dump_debug_info()
- 20.9.3.13 mysql_eof()
- 20.9.3.14 mysql_errno()
- 20.9.3.15 mysql_error()
- 20.9.3.16 mysql_escape_string()
- 20.9.3.17 mysql_fetch_field()
- 20.9.3.18 mysql_fetch_field_direct()
- 20.9.3.19 mysql_fetch_fields()
- 20.9.3.20 mysql_fetch_lengths()
- 20.9.3.21 mysql_fetch_row()
- 20.9.3.22 mysql_field_count()
- 20.9.3.23 mysql_field_seek()
- 20.9.3.24 mysql_field_tell()
- 20.9.3.25 mysql_free_result()
- 20.9.3.26 mysql_get_character_set_info()
- 20.9.3.27 mysql_get_client_info()
- 20.9.3.28 mysql_get_client_version()
- 20.9.3.29 mysql_get_host_info()
- 20.9.3.30 mysql_get_proto_info()
- 20.9.3.31 mysql_get_server_info()
- 20.9.3.32 mysql_get_server_version()
- 20.9.3.33 mysql_get_ssl_cipher()
- 20.9.3.34 mysql_hex_string()
- 20.9.3.35 mysql_info()
- 20.9.3.36 mysql_init()
- 20.9.3.37 mysql_insert_id()
- 20.9.3.38 mysql_kill()
- 20.9.3.39 mysql_library_end()
- 20.9.3.40 mysql_library_init()
- 20.9.3.41 mysql_list_dbs()
- 20.9.3.42 mysql_list_fields()
- 20.9.3.43 mysql_list_processes()
- 20.9.3.44 mysql_list_tables()
- 20.9.3.45 mysql_more_results()
- 20.9.3.46 mysql_next_result()
- 20.9.3.47 mysql_num_fields()
- 20.9.3.48 mysql_num_rows()
- 20.9.3.49 mysql_options()
- 20.9.3.50 mysql_ping()
- 20.9.3.51 mysql_query()
- 20.9.3.52 mysql_real_connect()
- 20.9.3.53 mysql_real_escape_string()
- 20.9.3.54 mysql_real_query()
- 20.9.3.55 mysql_refresh()
- 20.9.3.56 mysql_reload()
- 20.9.3.57 mysql_rollback()
- 20.9.3.58 mysql_row_seek()
- 20.9.3.59 mysql_row_tell()
- 20.9.3.60 mysql_select_db()
- 20.9.3.61 mysql_set_character_set()
- 20.9.3.62 mysql_set_local_infile_default()
- 20.9.3.63 mysql_set_local_infile_handler()
- 20.9.3.64 mysql_set_server_option()
- 20.9.3.65 mysql_shutdown()
- 20.9.3.66 mysql_sqlstate()
- 20.9.3.67 mysql_ssl_set()
- 20.9.3.68 mysql_stat()
- 20.9.3.69 mysql_store_result()
- 20.9.3.70 mysql_thread_id()
- 20.9.3.71 mysql_use_result()
- 20.9.3.72 mysql_warning_count()
MYSQL_RES *mysql_store_result(MYSQL *mysql)
Description
After invoking mysql_query() or
mysql_real_query(), you must
call mysql_store_result() or
mysql_use_result() for every
statement that successfully produces a result set
(SELECT,
SHOW,
DESCRIBE,
EXPLAIN,
CHECK TABLE, and so forth). You
must also call
mysql_free_result() after you
are done with the result set.
You don't have to call
mysql_store_result() or
mysql_use_result() for other
statements, but it does not do any harm or cause any notable
performance degradation if you call
mysql_store_result() in all
cases. You can detect whether the statement has a result set by
checking whether
mysql_store_result() returns a
nonzero value (more about this later on).
If you enable multiple-statement support, you should retrieve
results from calls to
mysql_query() or
mysql_real_query() by using a
loop that calls
mysql_next_result() to determine
whether there are more results. For an example, see
Section 20.9.12, “C API Support for Multiple Statement Execution”.
If you want to know whether a statement should return a result
set, you can use
mysql_field_count() to check for
this. See Section 20.9.3.22, “mysql_field_count()”.
mysql_store_result() reads the
entire result of a query to the client, allocates a
MYSQL_RES structure, and places the result
into this structure.
mysql_store_result() returns a
null pointer if the statement didn't return a result set (for
example, if it was an INSERT
statement).
mysql_store_result() also
returns a null pointer if reading of the result set failed. You
can check whether an error occurred by checking whether
mysql_error() returns a nonempty
string, mysql_errno() returns
nonzero, or mysql_field_count()
returns zero.
An empty result set is returned if there are no rows returned. (An empty result set differs from a null pointer as a return value.)
After you have called
mysql_store_result() and gotten
back a result that isn't a null pointer, you can call
mysql_num_rows() to find out how
many rows are in the result set.
You can call mysql_fetch_row()
to fetch rows from the result set, or
mysql_row_seek() and
mysql_row_tell() to obtain or
set the current row position within the result set.
Return Values
A MYSQL_RES result structure with the
results. NULL (0) if an error occurred.
Errors
mysql_store_result() resets
mysql_error() and
mysql_errno() if it succeeds.
-
Commands were executed in an improper order.
-
Out of memory.
-
The MySQL server has gone away.
-
The connection to the server was lost during the query.
-
An unknown error occurred.
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