Added create_synonym_db() procedure, which takes a source database name, and synonym name, and then creates a new database synonym with views pointing to all the tables within the source database.

Useful for adding an "i_s" or "p_s" synonym for the "information_schema" or "performance_schema" databases for example.

Author: MarkLeith

procedures/create_synonym_db.sql

@@ -0,0 +1,77 @@
+/* 
+ * Procedure: create_synonym_db()
+ *
+ * Parameters
+ *   in_db_name: The database you would like to create a synonym for.
+ *   in_synonym: The synonym you would like to create.
+ *
+ * Versions: 5.5+
+ */
+
+DROP PROCEDURE IF EXISTS create_synonym_db;
+
+DELIMITER $$
+
+CREATE PROCEDURE create_synonym_db(IN in_db_name VARCHAR(64), IN in_synonym VARCHAR(64))
+    SQL SECURITY INVOKER
+    COMMENT 'Parameters: in_db_name (VARCHAR(64)), in_synonym (VARCHAR(64))'
+BEGIN
+    DECLARE v_done bool DEFAULT FALSE;
+    DECLARE v_db_name_check VARCHAR(64);
+    DECLARE v_db_err_msg TEXT;
+    DECLARE v_table VARCHAR(64);
+
+    DECLARE db_doesnt_exist CONDITION FOR SQLSTATE '42000';
+    DECLARE db_name_exists CONDITION FOR SQLSTATE 'HY000';
+
+    DECLARE c_table_names CURSOR FOR 
+        SELECT TABLE_NAME FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_SCHEMA = in_db_name;
+
+    DECLARE CONTINUE HANDLER FOR NOT FOUND SET v_done = TRUE;
+
+    /* Check if the source database exists */
+    SELECT SCHEMA_NAME INTO v_db_name_check
+      FROM INFORMATION_SCHEMA.SCHEMATA
+     WHERE SCHEMA_NAME = in_db_name;
+
+    IF v_db_name_check IS NULL THEN
+        SET v_db_err_msg = CONCAT('Unknown database ', in_db_name);
+        SIGNAL SQLSTATE 'HY000'
+            SET MESSAGE_TEXT = v_db_err_msg;
+    END IF;
+
+    /* Check if a database of the synonym name already exists */
+    SELECT SCHEMA_NAME INTO v_db_name_check
+      FROM INFORMATION_SCHEMA.SCHEMATA
+     WHERE SCHEMA_NAME = in_synonym;
+
+    IF v_db_name_check = in_synonym THEN
+        SET v_db_err_msg = CONCAT('Can\'t create database ', in_synonym, '; database exists');
+        SIGNAL SQLSTATE 'HY000'
+            SET MESSAGE_TEXT = v_db_err_msg;
+    END IF;
+
+    /* All good, create the database and views */
+    SET @create_db_stmt := CONCAT('CREATE DATABASE ', in_synonym);
+    PREPARE create_db_stmt FROM @create_db_stmt;
+    EXECUTE create_db_stmt;
+    DEALLOCATE PREPARE create_db_stmt;
+
+    SET v_done = FALSE;
+    OPEN c_table_names;
+    c_table_names: LOOP
+        FETCH c_table_names INTO v_table;
+        IF v_done THEN
+            LEAVE c_table_names;
+        END IF;
+
+        SET @create_view_stmt = CONCAT('CREATE SQL SECURITY INVOKER VIEW ', in_synonym, '.', v_table, ' AS SELECT * FROM ', in_db_name, '.', v_table);
+        PREPARE create_view_stmt FROM @create_view_stmt;
+        EXECUTE create_view_stmt;
+        DEALLOCATE PREPARE create_view_stmt;
+    END LOOP;
+    CLOSE c_table_names;
+
+END$$
+
+DELIMITER ;