How to pass variables into MySql Procedure creation - mysql

Question

I want to be able to create some stored Procedures in different databases - so I want to be able to pass in the database name into the stored procedure creation statement.
SET #SourceDBName='dev';
DELIMITER //
CREATE PROCEDURE test ()
BEGIN
USE #SourceDBName;
SELECT * FROM agreed_relation;
END //
DELIMITER ;
How can I pass #SourceDBName into the CREATE PROCEDURE statement?

Answer 1

to pass in the database name into a stored procedure you must declare it in the procedure like this:
DELIMITER //
CREATE PROCEDURE test (IN idbname VARCHAR(20))
BEGIN
SELECT * FROM agreed_relation WHERE dbname = idbname;
END //
DELIMITER ;
After you create a Table like this where 'dbname' field it's the one your procedure will call:
create table agreed_relation
(
dbname varchar(30) not null
);
After insert some values you call the procedure and pass any dbname to the SELECT statament:
insert into agreed_relation(dbname) values('Oracle');
insert into agreed_relation(dbname) values('Mysql');
insert into agreed_relation(dbname) values('Mongodb');
Calling procedure and passing some value:
CALL test('Mysql');

Answer 2

14.1.16 CREATE PROCEDURE and CREATE FUNCTION Syntax
...
USE statements within stored routines are not permitted. When a
routine is invoked, an implicit USE db_name is performed (and undone
when the routine terminates). The causes the routine to have the given
default database while it executes. References to objects in databases
other than the routine default database should be qualified with the
appropriate database name.
...
An option to create the stored procedure in different databases is:
FIle: /path/to/file/myProcedure.sql
DROP PROCEDURE IF EXISTS `test`;
DELIMITER //
CREATE PROCEDURE `test`()
BEGIN
SELECT * FROM `agreed_relation`;
END//
DELIMITER ;
MySQL Command-Line:
mysql> USE `dev`;
Database changed
mysql> \. /path/to/file/myProcedure.sql
Query OK, 0 rows affected (0.00 sec)
mysql> USE `db1`;
Database changed
mysql> \. /path/to/file/myProcedure.sql
Query OK, 0 rows affected (0.00 sec)
mysql> USE `db2`;
Database changed
mysql> \. /path/to/file/myProcedure.sql
Query OK, 0 rows affected (0.00 sec)
mysql> USE `dev`;
Database changed
mysql> CALL `test`;
Empty set (0.01 sec)
Query OK, 0 rows affected (0.01 sec)
mysql> USE `db1`;
Database changed
mysql> CALL `test`;
Empty set (0.01 sec)
Query OK, 0 rows affected (0.01 sec)
mysql> USE `db2`;
Database changed
mysql> CALL `test`;
Empty set (0.01 sec)
Query OK, 0 rows affected (0.01 sec)
You can also create the stored procedure in a single database and pass the database name as a parameter to qualified the required objects and use 14.5 Prepared SQL Statement Syntax to execute it:
mysql> USE `dev`;
Database changed
mysql> DROP PROCEDURE IF EXISTS `test`;
Query OK, 0 rows affected (0.00 sec)
mysql> DELIMITER //
mysql> CREATE PROCEDURE `test`(`db_name` VARCHAR(64))
-> BEGIN
-> SET `db_name` := TRIM('\'' FROM QUOTE(`db_name`));
-> SET #`query` := CONCAT('SELECT * FROM `', `db_name`, '`.`agreed_relation`');
-> PREPARE `stmt` FROM #`query`;
-> EXECUTE `stmt`;
-> DEALLOCATE PREPARE `stmt`;
-> END//
Query OK, 0 rows affected (0.00 sec)
mysql> DELIMITER ;
mysql> CALL `test`('dev');
Empty set (0.01 sec)
Query OK, 0 rows affected (0.01 sec)
mysql> CALL `test`('db1');
Empty set (0.01 sec)
Query OK, 0 rows affected (0.01 sec)
mysql> CALL `test`('db2');
Empty set (0.01 sec)
Query OK, 0 rows affected (0.01 sec)