-- Copyright (c) 2015, Oracle and/or its affiliates. All rights reserved. -- -- This program is free software; you can redistribute it and/or modify -- it under the terms of the GNU General Public License as published by -- the Free Software Foundation; version 2 of the License. -- -- This program is distributed in the hope that it will be useful, -- but WITHOUT ANY WARRANTY; without even the implied warranty of -- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the -- GNU General Public License for more details. -- -- You should have received a copy of the GNU General Public License -- along with this program; if not, write to the Free Software -- Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA DROP PROCEDURE IF EXISTS table_exists; DELIMITER $$ CREATE DEFINER='mariadb.sys'@'localhost' PROCEDURE table_exists ( IN in_db VARCHAR(64), IN in_table VARCHAR(64), OUT out_exists ENUM('', 'BASE TABLE', 'VIEW', 'TEMPORARY', 'SEQUENCE', 'SYSTEM VIEW') ) COMMENT ' Description ----------- Tests whether the table specified in in_db and in_table exists either as a regular table, or as a temporary table. The returned value corresponds to the table that will be used, so if there''s both a temporary and a permanent table with the given name, then ''TEMPORARY'' will be returned. Parameters ----------- in_db (VARCHAR(64)): The database name to check for the existence of the table in. in_table (VARCHAR(64)): The name of the table to check the existence of. out_exists ENUM('''', ''BASE TABLE'', ''VIEW'', ''TEMPORARY''): The return value: whether the table exists. The value is one of: * '''' - the table does not exist neither as a base table, view, sequence nor temporary table. * ''BASE TABLE'' - the table name exists as a permanent base table table. * ''VIEW'' - the table name exists as a view. * ''TEMPORARY'' - the table name exists as a temporary table. * ''SEQUENCE'' - the table name exists as a sequence. * ''SYSTEM VIEW'' - the table name exists as a system view. Example -------- mysql> CREATE DATABASE db1; Query OK, 1 row affected (0.07 sec) mysql> use db1; Database changed mysql> CREATE TABLE t1 (id INT PRIMARY KEY); Query OK, 0 rows affected (0.08 sec) mysql> CREATE TABLE t2 (id INT PRIMARY KEY); Query OK, 0 rows affected (0.08 sec) mysql> CREATE view v_t1 AS SELECT * FROM t1; Query OK, 0 rows affected (0.00 sec) mysql> CREATE TEMPORARY TABLE t1 (id INT PRIMARY KEY); Query OK, 0 rows affected (0.00 sec) mysql> CALL sys.table_exists(''db1'', ''t1'', @exists); SELECT @exists; Query OK, 0 rows affected (0.00 sec) +------------+ | @exists | +------------+ | TEMPORARY | +------------+ 1 row in set (0.00 sec) mysql> CALL sys.table_exists(''db1'', ''t2'', @exists); SELECT @exists; Query OK, 0 rows affected (0.00 sec) +------------+ | @exists | +------------+ | BASE TABLE | +------------+ 1 row in set (0.01 sec) mysql> CALL sys.table_exists(''db1'', ''v_t1'', @exists); SELECT @exists; Query OK, 0 rows affected (0.00 sec) +---------+ | @exists | +---------+ | VIEW | +---------+ 1 row in set (0.00 sec) MariaDB [sys]> CALL sys.table_exists(''db1'', ''s'', @exists); SELECT @exists; Query OK, 0 rows affected (0.006 sec) +----------+ | @exists | +----------+ | SEQUENCE | +----------+ 1 row in set (0.000 sec) MariaDB [sys]> CALL table_exists(''information_schema'', ''user_variables'', @exists); SELECT @exists; Query OK, 0 rows affected (0.003 sec) +-------------+ | @exists | +-------------+ | SYSTEM VIEW | +-------------+ 1 row in set (0.001 sec) mysql> CALL sys.table_exists(''db1'', ''t3'', @exists); SELECT @exists; Query OK, 0 rows affected (0.01 sec) +---------+ | @exists | +---------+ | | +---------+ 1 row in set (0.00 sec) ' SQL SECURITY INVOKER NOT DETERMINISTIC CONTAINS SQL BEGIN DECLARE v_error BOOLEAN DEFAULT FALSE; DECLARE db_quoted VARCHAR(64); DECLARE table_quoted VARCHAR(64); DECLARE v_table_type VARCHAR(16) DEFAULT ''; DECLARE v_system_db BOOLEAN DEFAULT LOWER(in_db) IN ('information_schema', 'performance_schema'); DECLARE CONTINUE HANDLER FOR 1050 SET v_error = TRUE; DECLARE CONTINUE HANDLER FOR 1146 SET v_error = TRUE; SET out_exists = ''; SET db_quoted = sys.quote_identifier(in_db); SET table_quoted = sys.quote_identifier(in_table); -- Verify whether the table name exists as a normal table IF (EXISTS(SELECT 1 FROM information_schema.TABLES WHERE TABLE_SCHEMA = in_db AND TABLE_NAME = in_table)) THEN -- Unfortunately the only way to determine whether there is also a temporary table is to try to create -- a temporary table with the same name. If it succeeds the table didn't exist as a temporary table. IF v_system_db = FALSE THEN SET @sys.tmp.table_exists.SQL = CONCAT('CREATE TEMPORARY TABLE ', db_quoted, '.', table_quoted, '(id INT PRIMARY KEY)'); PREPARE stmt_create_table FROM @sys.tmp.table_exists.SQL; EXECUTE stmt_create_table; DEALLOCATE PREPARE stmt_create_table; -- The temporary table was created, i.e. it didn't exist. Remove it again so we don't leave garbage around. SET @sys.tmp.table_exists.SQL = CONCAT('DROP TEMPORARY TABLE ', db_quoted, '.', table_quoted); PREPARE stmt_drop_table FROM @sys.tmp.table_exists.SQL; EXECUTE stmt_drop_table; DEALLOCATE PREPARE stmt_drop_table; END IF; IF (v_error) THEN SET out_exists = 'TEMPORARY'; ELSE SET v_table_type = (SELECT TABLE_TYPE FROM information_schema.TABLES WHERE TABLE_SCHEMA = in_db AND TABLE_NAME = in_table); -- Don't fail on table_type='SYSTEM VERSIONED' -- but return 'BASE TABLE' for compatibility with existing tooling IF v_table_type = 'SYSTEM VERSIONED' THEN SET out_exists = 'BASE TABLE'; ELSE SET out_exists = v_table_type; END IF; END IF; ELSE -- Check whether a temporary table exists with the same name. -- If it does it's possible to SELECT from the table without causing an error. -- If it does not exist even a PREPARE using the table will fail. IF v_system_db = FALSE THEN SET @sys.tmp.table_exists.SQL = CONCAT('SELECT COUNT(*) FROM ', db_quoted, '.', table_quoted); PREPARE stmt_select FROM @sys.tmp.table_exists.SQL; IF (NOT v_error) THEN DEALLOCATE PREPARE stmt_select; SET out_exists = 'TEMPORARY'; END IF; END IF; END IF; END$$ DELIMITER ;