MySQL Tutorial/Math Numeric Functions/Arithmetic Operators
Версия от 13:44, 26 мая 2010; (обсуждение)
Содержание
Addition: +
mysql> SELECT 3+5;
+-----+
| 3+5 |
+-----+
| 8 |
+-----+
1 row in set (0.00 sec)
Division: /
mysql>
mysql> SELECT 3/5;
+--------+
| 3/5 |
+--------+
| 0.6000 |
+--------+
1 row in set (0.00 sec)
mysql>
Division by zero produces a NULL result
mysql>
mysql> SELECT 102/(1-1);
+-----------+
| 102/(1-1) |
+-----------+
| NULL |
+-----------+
1 row in set (0.00 sec)
mysql>
mysql>
mysql>
Multiplication: *
mysql>
mysql> SELECT 3*5;
+-----+
| 3*5 |
+-----+
| 15 |
+-----+
1 row in set (0.00 sec)
mysql>
Subtraction: -
mysql>
mysql> SELECT 3-5;
+-----+
| 3-5 |
+-----+
| -2 |
+-----+
1 row in set (0.00 sec)
mysql>
Unary minus: -
This operator changes the sign of the argument.
mysql>
mysql> SELECT -2;
+----+
| -2 |
+----+
| -2 |
+----+
1 row in set (0.02 sec)
mysql>
Using Arithmetic Operators in select statement
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 (0.09 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 (0.02 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 (0.01 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>
mysql> select salary, salary + 1234.56 from Employee;
+---------+------------------+
| salary | salary + 1234.56 |
+---------+------------------+
| 1234.56 | 2469.12 |
| 6661.78 | 7896.34 |
| 6544.78 | 7779.34 |
| 2344.78 | 3579.34 |
| 2334.78 | 3569.34 |
| 4322.78 | 5557.34 |
| 7897.78 | 9132.34 |
| 1232.78 | 2467.34 |
+---------+------------------+
8 rows in set (0.00 sec)
mysql>
mysql>
mysql>
mysql>
mysql> drop table Employee;
Query OK, 0 rows affected (0.01 sec)
mysql>