SQL/MySQL/Procedure Function/IF statement
Содержание
Check version with if statement
mysql>
mysql> delimiter $$
mysql>
mysql> CREATE PROCEDURE myProc()
-> BEGIN
->
-> IF (INSTR(version(),"alpha")>0) THEN
-> SELECT "Alpha release of MySQL";
-> ELSEIF (INSTR(version(),"beta")>0) THEN
-> SELECT "Beta release of MySQL";
-> ELSE
-> SELECT "Production release of MySQL";
-> END IF;
->
->
-> END$$
Query OK, 0 rows affected (0.00 sec)
mysql>
mysql> delimiter ;
mysql>
mysql> call myProc();
+-----------------------------+
| Production release of MySQL |
+-----------------------------+
| Production release of MySQL |
+-----------------------------+
1 row in set (0.00 sec)
Query OK, 0 rows affected (0.00 sec)
mysql>
mysql> drop procedure myProc;
Query OK, 0 rows affected (0.00 sec)
mysql>
mysql>
IF
mysql>
mysql>
mysql> DELIMITER //
mysql> CREATE FUNCTION delivery_day_shipping (delivery_day INT(1)) RETURNS INT(2)
-> BEGIN
->
-> DECLARE shipping_cost INT(2) DEFAULT 0;
->
-> IF delivery_day = 1 THEN
-> SET shipping_cost = 20;
-> ELSEIF delivery_day = 2 THEN
-> SET shipping_cost = 15;
-> ELSEIF delivery_day = 3 THEN
-> SET shipping_cost = 10;
-> ELSE
-> SET shipping_cost = 5;
-> END IF;
->
-> RETURN shipping_cost;
->
-> END
-> //
ERROR 1304 (42000): FUNCTION delivery_day_shipping already exists
mysql> DELIMITER ;
mysql>
mysql>
IF statement in a LOOP statement
mysql>
mysql> delimiter $$
mysql>
mysql> CREATE PROCEDURE myProc()
-> BEGIN
->
-> DECLARE i int;
-> SET i=0;
-> loop1: REPEAT
-> SET i=i+1;
-> IF MOD(i,2)<>0 THEN /*Even number - try again*/
-> SELECT CONCAT(i," is an odd number");
-> END IF;
-> UNTIL i >= 10
-> END REPEAT;
-> END$$
Query OK, 0 rows affected (0.00 sec)
mysql>
mysql> delimiter ;
mysql> call myProc();
+-------------------------------+
| CONCAT(i," is an odd number") |
+-------------------------------+
| 1 is an odd number |
+-------------------------------+
1 row in set (0.00 sec)
+-------------------------------+
| CONCAT(i," is an odd number") |
+-------------------------------+
| 3 is an odd number |
+-------------------------------+
1 row in set (0.33 sec)
+-------------------------------+
| CONCAT(i," is an odd number") |
+-------------------------------+
| 5 is an odd number |
+-------------------------------+
1 row in set (0.33 sec)
+-------------------------------+
| CONCAT(i," is an odd number") |
+-------------------------------+
| 7 is an odd number |
+-------------------------------+
1 row in set (0.34 sec)
+-------------------------------+
| CONCAT(i," is an odd number") |
+-------------------------------+
| 9 is an odd number |
+-------------------------------+
1 row in set (0.34 sec)
Query OK, 0 rows affected (0.34 sec)
mysql> drop procedure myProc;
Query OK, 0 rows affected (0.00 sec)
mysql>
If statement with ELSEIF and ELSE
mysql>
mysql> delimiter $$
mysql> CREATE PROCEDURE myProc(normal_price NUMERIC(8,2),OUT discount_price NUMERIC(8,2))
-> NO SQL
-> BEGIN
-> IF (normal_price>500) THEN
-> SET discount_price=normal_price*.8;
-> ELSEIF (normal_price>100) THEN
-> SET discount_price=normal_price*.9;
->
-> ELSE
-> SET discount_price=normal_price;
-> END IF;
-> select discount_price;
-> END$$
Query OK, 0 rows affected (0.00 sec)
mysql> delimiter ;
mysql>
mysql> set @p = 600;
Query OK, 0 rows affected (0.00 sec)
mysql> set @dp = 0;
Query OK, 0 rows affected (0.00 sec)
mysql>
mysql> call myProc(@p, @dp);
+----------------+
| discount_price |
+----------------+
| 480.00 |
+----------------+
1 row in set (0.00 sec)
Query OK, 0 rows affected (0.00 sec)
mysql> select @dp;
+--------+
| @dp |
+--------+
| 480.00 |
+--------+
1 row in set (0.00 sec)
mysql> drop procedure myProc;
Query OK, 0 rows affected (0.00 sec)
mysql>
Using OR in an IF statement
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 (0.01 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 (0.02 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 $$
mysql> CREATE PROCEDURE myProc(in_employee_id INT, in_new_salary NUMERIC(8,2))
-> DETERMINISTIC
-> BEGIN
-> IF in_new_salary <5000 OR in_new_salary > 500000 THEN
-> SELECT "Illegal salary; salary must be between $5,000 and $500,000";
-> ELSE
-> UPDATE employee SET salary=in_new_salary
-> WHERE id=in_employee_id;
-> END IF;
-> END$$
Query OK, 0 rows affected (0.00 sec)
mysql> delimiter ;
mysql>
mysql> call myProc(1, 6000);
Query OK, 1 row affected (0.02 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 | 6000.00 | 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> call myProc(1,4000);
+------------------------------------------------------------+
| Illegal salary; salary must be between $5,000 and $500,000 |
+------------------------------------------------------------+
| Illegal salary; salary must be between $5,000 and $500,000 |
+------------------------------------------------------------+
1 row in set (0.00 sec)
Query OK, 0 rows affected (0.01 sec)
mysql>
mysql> DROP PROCEDURE myProc;
Query OK, 0 rows affected (0.02 sec)
mysql>
mysql>
mysql>
mysql>
mysql>
mysql> drop table Employee;
Query OK, 0 rows affected (0.00 sec)
mysql>
mysql>