MySQL Tutorial/Procedure Function/Function Returning
Содержание
Check function parameter and return value
mysql>
mysql> delimiter $$
mysql>
mysql> CREATE FUNCTION myFunction(in_status CHAR(1))
-> RETURNS VARCHAR(20)
-> BEGIN
-> IF in_status = "O" THEN
-> RETURN("Overdue");
-> ELSEIF in_status = "U" THEN
-> RETURN("Up to date");
-> ELSEIF in_status = "N" THEN
-> RETURN("New");
-> END IF;
-> END$$
Query OK, 0 rows affected (0.00 sec)
mysql>
mysql> delimiter ;
mysql>
mysql> select myFunction("O");
+-----------------+
| myFunction("O") |
+-----------------+
| Overdue |
+-----------------+
1 row in set (0.00 sec)
mysql>
mysql> select myFunction("U");
+-----------------+
| myFunction("U") |
+-----------------+
| Up to date |
+-----------------+
1 row in set (0.00 sec)
mysql>
mysql> select myFunction("N");
+-----------------+
| myFunction("N") |
+-----------------+
| New |
+-----------------+
1 row in set (0.00 sec)
mysql>
mysql>
mysql> drop function myFunction;
Query OK, 0 rows affected (0.00 sec)
mysql>
mysql>
Returning Decimal from the function
mysql>
mysql> DELIMITER //
mysql>
mysql> CREATE FUNCTION myFunction (rush_ship INT(10)) RETURNS DECIMAL(10,2)
-> BEGIN
->
-> DECLARE rush_shipping_cost DECIMAL(10,2);
->
-> CASE rush_ship
-> WHEN 1 THEN
-> SET rush_shipping_cost = 20.00;
-> WHEN 2 THEN
-> SET rush_shipping_cost = 15.00;
-> WHEN 3 THEN
-> SET rush_shipping_cost = 10.00;
-> ELSE
-> SET rush_shipping_cost = 0.00;
-> END CASE;
->
-> RETURN rush_shipping_cost;
->
-> END
-> //
Query OK, 0 rows affected (0.00 sec)
mysql> DELIMITER ;
mysql>
mysql> select myFunction(1);
+---------------+
| myFunction(1) |
+---------------+
| 20.00 |
+---------------+
1 row in set (0.00 sec)
mysql>
mysql> drop function myFunction;
Query OK, 0 rows affected (0.02 sec)
Return integer value from a function
mysql>
mysql>
mysql>
mysql> CREATE TABLE Employee(
-> id int,
-> first_name VARCHAR(15),
-> last_name VARCHAR(15),
-> start_date DATE,
-> end_date DATE,
-> salary FLOAT(8,2),
-> city VARCHAR(10),
-> description VARCHAR(15)
-> );
Query OK, 0 rows affected (0.01 sec)
mysql>
mysql>
mysql> insert into Employee(id,first_name, last_name, start_date, end_Date, salary, City, Description)
-> values (1,"Jason", "Martin", "19960725", "20060725", 1234.56, "Toronto", "Programmer");
Query OK, 1 row affected (0.00 sec)
mysql>
mysql> insert into Employee(id,first_name, last_name, start_date, end_Date, salary, City, Description)
-> values(2,"Alison", "Mathews", "19760321", "19860221", 6661.78, "Vancouver","Tester");
Query OK, 1 row affected (0.00 sec)
mysql>
mysql> insert into Employee(id,first_name, last_name, start_date, end_Date, salary, City, Description)
-> values(3,"James", "Smith", "19781212", "19900315", 6544.78, "Vancouver","Tester");
Query OK, 1 row affected (0.00 sec)
mysql>
mysql> insert into Employee(id,first_name, last_name, start_date, end_Date, salary, City, Description)
-> values(4,"Celia", "Rice", "19821024", "19990421", 2344.78, "Vancouver","Manager");
Query OK, 1 row affected (0.00 sec)
mysql>
mysql> insert into Employee(id,first_name, last_name, start_date, end_Date, salary, City, Description)
-> values(5,"Robert", "Black", "19840115", "19980808", 2334.78, "Vancouver","Tester");
Query OK, 1 row affected (0.00 sec)
mysql>
mysql> insert into Employee(id,first_name, last_name, start_date, end_Date, salary, City, Description)
-> values(6,"Linda", "Green", "19870730", "19960104", 4322.78,"New York", "Tester");
Query OK, 1 row affected (0.02 sec)
mysql>
mysql> insert into Employee(id,first_name, last_name, start_date, end_Date, salary, City, Description)
-> values(7,"David", "Larry", "19901231", "19980212", 7897.78,"New York", "Manager");
Query OK, 1 row affected (0.00 sec)
mysql>
mysql> insert into Employee(id,first_name, last_name, start_date, end_Date, salary, City, Description)
-> values(8,"James", "Cat", "19960917", "20020415", 1232.78,"Vancouver", "Tester");
Query OK, 1 row affected (0.00 sec)
mysql>
mysql> select * from Employee;
+------+------------+-----------+------------+------------+---------+-----------+-------------+
| id | first_name | last_name | start_date | end_date | salary | city | description |
+------+------------+-----------+------------+------------+---------+-----------+-------------+
| 1 | Jason | Martin | 1996-07-25 | 2006-07-25 | 1234.56 | Toronto | Programmer |
| 2 | Alison | Mathews | 1976-03-21 | 1986-02-21 | 6661.78 | Vancouver | Tester |
| 3 | James | Smith | 1978-12-12 | 1990-03-15 | 6544.78 | Vancouver | Tester |
| 4 | Celia | Rice | 1982-10-24 | 1999-04-21 | 2344.78 | Vancouver | Manager |
| 5 | Robert | Black | 1984-01-15 | 1998-08-08 | 2334.78 | Vancouver | Tester |
| 6 | Linda | Green | 1987-07-30 | 1996-01-04 | 4322.78 | New York | Tester |
| 7 | David | Larry | 1990-12-31 | 1998-02-12 | 7897.78 | New York | Manager |
| 8 | James | Cat | 1996-09-17 | 2002-04-15 | 1232.78 | Vancouver | Tester |
+------+------------+-----------+------------+------------+---------+-----------+-------------+
8 rows in set (0.00 sec)
mysql>
mysql>
mysql>
mysql> delimiter $$
mysql> CREATE FUNCTION myFunction (in_dob datetime) returns int
-> NO SQL
-> BEGIN
-> DECLARE l_age INT;
-> IF DATE_FORMAT(NOW(),"00-%m-%d") >= DATE_FORMAT(in_dob,"00-%m-%d") THEN
-> SET l_age=DATE_FORMAT(NOW(),"%Y")-DATE_FORMAT(in_dob,"%Y");
-> ELSE
-> SET l_age=DATE_FORMAT(NOW(),"%Y")-DATE_FORMAT(in_dob,"%Y")-1;
-> END IF;
-> RETURN(l_age);
->
-> END$$
Query OK, 0 rows affected (0.00 sec)
mysql> delimiter ;
mysql>
mysql> select myFunction(start_date) from employee;
+------------------------+
| myFunction(start_date) |
+------------------------+
| 10 |
| 31 |
| 28 |
| 24 |
| 23 |
| 19 |
| 16 |
| 10 |
+------------------------+
8 rows in set (0.00 sec)
mysql>
mysql> drop function myFunction;
Query OK, 0 rows affected (0.00 sec)
mysql>
mysql>
mysql>
mysql>
mysql> drop table Employee;
Query OK, 0 rows affected (0.00 sec)
mysql>
mysql>
Return NUMERIC(8,2) from a function
mysql>
mysql>
mysql> delimiter $$
mysql> CREATE FUNCTION myFunction(normal_price NUMERIC(8,2))
-> RETURNS NUMERIC(8,2)
-> BEGIN
->
-> DECLARE discount_price NUMERIC(8,2);
->
-> IF (normal_price>500) THEN
-> SET discount_price=normal_price*.8;
-> ELSEIF (normal_price>100) THEN
-> SET discount_price=normal_price*.9;
-> ELSE
-> SET discount_price=normal_price;
-> END IF;
-> RETURN(discount_price);
-> END$$
Query OK, 0 rows affected (0.00 sec)
mysql> delimiter ;
mysql>
mysql> select myFunction(123.123);
+---------------------+
| myFunction(123.123) |
+---------------------+
| 110.81 |
+---------------------+
1 row in set, 2 warnings (0.02 sec)
mysql>
mysql>
mysql> drop function myFunction;
Query OK, 0 rows affected (0.00 sec)
mysql>
mysql>
Return value from a function
mysql>
mysql> delimiter $$
mysql>
mysql> CREATE FUNCTION myFunction(
-> in_title VARCHAR(4),
-> in_gender CHAR(1),
-> in_firstname VARCHAR(20),
-> in_middle_initial CHAR(1),
-> in_surname VARCHAR(20))
->
-> RETURNS VARCHAR(60)
-> BEGIN
-> DECLARE l_title VARCHAR(4);
-> DECLARE l_name_string VARCHAR(60);
->
-> IF ISNULL(in_title) THEN
-> IF in_gender="M" THEN
-> SET l_title="Mr";
-> ELSE
-> SET l_title="Ms";
-> END IF;
-> END IF;
->
-> IF ISNULL(in_middle_initial) THEN
-> SET l_name_string=CONCAT(l_title," ",in_firstname," ",in_surname);
-> ELSE
-> SET l_name_string=CONCAT(l_title," ",in_firstname," ",
-> in_middle_initial," ",in_surname);
-> END IF;
->
-> RETURN(l_name_string);
-> END$$
Query OK, 0 rows affected (0.00 sec)
mysql>
mysql> delimiter ;
mysql>
mysql> select myFunction("Mrs","M","First","Middle","Last");
+-----------------------------------------------+
| myFunction("Mrs","M","First","Middle","Last") |
+-----------------------------------------------+
| NULL |
+-----------------------------------------------+
1 row in set, 1 warning (0.00 sec)
mysql>
mysql>
mysql> select myFunction(null,"M","First","Middle","Last");
+----------------------------------------------+
| myFunction(null,"M","First","Middle","Last") |
+----------------------------------------------+
| Mr First M Last |
+----------------------------------------------+
1 row in set, 1 warning (0.00 sec)
mysql>
mysql> drop function myFunction;
Query OK, 0 rows affected (0.00 sec)
mysql>
mysql>
Using the returning value from a user-defined function in order by clause
mysql>
mysql>
mysql> CREATE TABLE Employee(
-> id int,
-> first_name VARCHAR(15),
-> last_name VARCHAR(15),
-> start_date DATE,
-> end_date DATE,
-> salary FLOAT(8,2),
-> city VARCHAR(10),
-> description VARCHAR(15)
-> );
Query OK, 0 rows affected (0.02 sec)
mysql>
mysql>
mysql> insert into Employee(id,first_name, last_name, start_date, end_Date, salary, City, Description)
-> values (1,"Jason", "Martin", "19960725", "20060725", 1234.56, "Toronto", "Programmer");
Query OK, 1 row affected (0.00 sec)
mysql>
mysql> insert into Employee(id,first_name, last_name, start_date, end_Date, salary, City, Description)
-> values(2,"Alison", "Mathews", "19760321", "19860221", 6661.78, "Vancouver","Tester");
Query OK, 1 row affected (0.00 sec)
mysql>
mysql> insert into Employee(id,first_name, last_name, start_date, end_Date, salary, City, Description)
-> values(3,"James", "Smith", "19781212", "19900315", 6544.78, "Vancouver","Tester");
Query OK, 1 row affected (0.00 sec)
mysql>
mysql> insert into Employee(id,first_name, last_name, start_date, end_Date, salary, City, Description)
-> values(4,"Celia", "Rice", "19821024", "19990421", 2344.78, "Vancouver","Manager");
Query OK, 1 row affected (0.00 sec)
mysql>
mysql> insert into Employee(id,first_name, last_name, start_date, end_Date, salary, City, Description)
-> values(5,"Robert", "Black", "19840115", "19980808", 2334.78, "Vancouver","Tester");
Query OK, 1 row affected (0.00 sec)
mysql>
mysql> insert into Employee(id,first_name, last_name, start_date, end_Date, salary, City, Description)
-> values(6,"Linda", "Green", "19870730", "19960104", 4322.78,"New York", "Tester");
Query OK, 1 row affected (0.00 sec)
mysql>
mysql> insert into Employee(id,first_name, last_name, start_date, end_Date, salary, City, Description)
-> values(7,"David", "Larry", "19901231", "19980212", 7897.78,"New York", "Manager");
Query OK, 1 row affected (0.00 sec)
mysql>
mysql> insert into Employee(id,first_name, last_name, start_date, end_Date, salary, City, Description)
-> values(8,"James", "Cat", "19960917", "20020415", 1232.78,"Vancouver", "Tester");
Query OK, 1 row affected (0.00 sec)
mysql>
mysql> select * from Employee;
+------+------------+-----------+------------+------------+---------+-----------+-------------+
| id | first_name | last_name | start_date | end_date | salary | city | description |
+------+------------+-----------+------------+------------+---------+-----------+-------------+
| 1 | Jason | Martin | 1996-07-25 | 2006-07-25 | 1234.56 | Toronto | Programmer |
| 2 | Alison | Mathews | 1976-03-21 | 1986-02-21 | 6661.78 | Vancouver | Tester |
| 3 | James | Smith | 1978-12-12 | 1990-03-15 | 6544.78 | Vancouver | Tester |
| 4 | Celia | Rice | 1982-10-24 | 1999-04-21 | 2344.78 | Vancouver | Manager |
| 5 | Robert | Black | 1984-01-15 | 1998-08-08 | 2334.78 | Vancouver | Tester |
| 6 | Linda | Green | 1987-07-30 | 1996-01-04 | 4322.78 | New York | Tester |
| 7 | David | Larry | 1990-12-31 | 1998-02-12 | 7897.78 | New York | Manager |
| 8 | James | Cat | 1996-09-17 | 2002-04-15 | 1232.78 | Vancouver | Tester |
+------+------------+-----------+------------+------------+---------+-----------+-------------+
8 rows in set (0.00 sec)
mysql>
mysql>
mysql>
mysql> delimiter $$
mysql>
mysql> CREATE FUNCTION myFunction(in_rep_id INT)
-> RETURNS INT
-> READS SQL DATA
-> BEGIN
-> DECLARE customer_count INT;
->
-> SELECT COUNT(*)
-> INTO customer_count
-> FROM employee
-> WHERE id=in_rep_id;
->
-> RETURN(customer_count);
->
-> END$$
Query OK, 0 rows affected (0.00 sec)
mysql>
mysql> delimiter ;
mysql>
mysql> SELECT id,myFunction(id)
-> FROM employee
-> WHERE myFunction(id)>0
-> ORDER BY myFunction(id) desc;
+------+----------------+
| id | myFunction(id) |
+------+----------------+
| 1 | 1 |
| 2 | 1 |
| 3 | 1 |
| 4 | 1 |
| 5 | 1 |
| 6 | 1 |
| 7 | 1 |
| 8 | 1 |
+------+----------------+
8 rows in set (0.02 sec)
mysql>
mysql> drop function myFunction;
Query OK, 0 rows affected (0.01 sec)
mysql>
mysql>
mysql>
mysql>
mysql> drop table Employee;
Query OK, 0 rows affected (0.00 sec)
mysql>
mysql>