Procedure in MariaDB

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MariaDB Procedure
A procedure in MariaDB can be simply understood as a stored program that is used to pass parameters into it. However, unlike functions, it does not return a value.

MariaDB Create Procedure:

Syntax: To create a procedure in MariaDB database. 

CREATE   
[ DEFINER = { CURRENT_USER | user_name } ]   
PROCEDURE procedure_name   
[ (parameter data type, parameter data type) ]  
[ LANGUAGE SQL  
| DETERMINISTIC  
| NOT DETERMINISTIC  
| { CONTAINS SQL   
  | NO SQL  
  | READS SQL DATA  
  | MODIFIES SQL DATA }  
| SQL SECURITY { DEFINER | INVOKER }  
| COMMENT 'comment_value'  
BEGIN  
   declaration_section  
   executable_section  
END;

Parameters:

  • DEFINER clause: It is an optional clause which is used to specify a definer, by including the DEFINER clause where user_name is the definer for the procedure. By default, the definer is the user that created the procedure.
  • procedure_name: It is used to specify the name of the procedure.
  • Parameters: It is used to specify the parameters passed to the procedure. It can be of three types:
      1. IN:
        It is used to specify that the parameter can be referenced by the procedure, however its value can not be overwritten by the procedure.

      2. OUT:
        It is used to specify that the parameter can not be referenced by the procedure, however its value can be overwritten by the procedure.
      3. IN OUT:
        It is used to specify that the parameter can be referenced by the procedure, however its value can be overwritten by the procedure.
  • LANGUAGE SQL: It is used to specify the Language SQL in the syntax for portability. It has no impact on the procedure.
  • DETERMINISTIC: It is used to specify that the procedure will always return one result given a set of input parameters.
  • NOT DETERMINISTIC: It is used to specify that the procedure may return a different result given a set of input parameters.
  • CONTAINS SQL: It is used to specify an informative clause to tell that the procedure contains SQL, but the database does not verify that this is true.
  • NO SQL: It is used to specify an informative clause that is not used and will have no impact on the procedure.
  • READS SQL DATA: It is used to specify an informative clause to tell that the procedure will read data using SELECT statements but does not modify any data.
  • MODIFIES SQL DATA: It is used to specify an informative clause to tell that the procedure will modify SQL data using INSERT, UPDATE, DELETE, or other DDL statements.
  • declaration_section: It is used to specify the place in the procedure to declare local variables.
  • executable_section: It is used to specify the place in the procedure to enter the code for the procedure.

Example: 

DELIMITER //  
CREATE procedure Calculate ( OUT final_value INT )  
DETERMINISTIC  
BEGIN  
   DECLARE total_value INT;  
   SET total_sum = 10;  
   label1: WHILE total_sum <= 100 DO  
     SET total_sum = total_sum * 10;  
   END WHILE label1;  
   SET final_value = total_sum;  
END; //  
DELIMITER ;

Explanation:
Here we are creating a procedure Calculate in MariaDB database.

MariaDB DROP Procedure:

In MariaDB, we can also drop an already existing procedure from the database.

Syntax: To drop a procedure from MariaDB database. 

DROP PROCEDURE [ IF EXISTS ] proc_name;

Parameters:
proc_name: It is used to specify the name of the procedure to drop.

Example: 

DROP PROCEDURE Calculate;