MySQL supports Stored Procedures which can execute set of codes by applying relevant business logics. In this post we will see how to create a stored procedure and execute it.
Let us create the following tables
CREATE TABLE items(item_id INT, item_description VARCHAR(100));
CREATE TABLE sales(sales_id INT auto_increment KEY,item_id INT, sales_date DATETIME, sales_amount DECIMAL(12,2));
INSERT INTO items VALUES (1,'Television');
INSERT INTO items VALUES (2,'Mobile');
INSERT INTO items VALUES (3,'laptop');
INSERT INTO sales(item_id,sales_date,sales_amount) VALUES (1,'2014-01-01',1200);
INSERT INTO sales(item_id,sales_date,sales_amount) VALUES (2,'2014-01-02',200);
INSERT INTO sales(item_id,sales_date,sales_amount) VALUES (3,'2014-01-09',1700);
INSERT INTO sales(item_id,sales_date,sales_amount) VALUES (3,'2014-01-29',1700);
INSERT INTO sales(item_id,sales_date,sales_amount) VALUES (3,'2014-02-11',1700);
INSERT INTO sales(item_id,sales_date,sales_amount) VALUES (1,'2014-02-16',1200);
INSERT INTO sales(item_id,sales_date,sales_amount) VALUES (2,'2014-02-16',200);
INSERT INTO sales(item_id,sales_date,sales_amount) VALUES (2,'2014-02-20',200);
INSERT INTO sales(item_id,sales_date,sales_amount) VALUES (2,'2014-02-20',200);
INSERT INTO sales(item_id,sales_date,sales_amount) VALUES (2,'2014-02-22',200);
INSERT INTO sales(item_id,sales_date,sales_amount) VALUES (3,'2014-02-24',1700);
INSERT INTO sales(item_id,sales_date,sales_amount) VALUES (1,'2014-02-24',1200);
Suppose you want to create a stored procedure which will accept item_description and returns the total sales_amount for the enire period, you can do it as shown below
DELIMITER $$
CREATE PROCEDURE Test.usp_get_sales
(
param_item_description VARCHAR(100)
)
BEGIN
SELECT item_description,SUM(sales_amount) AS sales_amount FROM items NATURAL
JOIN sales
WHERE item_description=param_item_description
GROUP BY item_description;
END;
$$
DELIMITER;
Note that the creation of the stored procedure starts with setting the Delimiter $$. The default delimiter for MySQL statements are semicolon so in order to instruct the MySQL engine about the start and end of the stored procedure block, you need to use a different delimiter (which in this case $$ is used).
Now you can execute a stored procedure using CALL keyword as shown below.
Execution 1
CALL usp_get_sales('Television');
When you execute the above code, the result is
Item_description sales_amount Television 3600.00
Execution 2
CALL usp_get_sales('laptop');
When you execute the above code, the result is
Item_description sales_amount laptop 6800.00
Note: The parameters do not start with @ like we use in SQL Server. So in order to differentiate between the actual column name and parameter name, the name param_item_description is used. You may need to use different naming conventions as you like.
I have previously written a similar article here: MySQL – How to Create Stored Procedure.
Reference: Pinal Dave https://blog.sqlauthority.com/ )
