自动计算二个字段的值赋给另一字段sql:
$sql ="update table set sum = mathe +language";
求一个字段列的数据总和:
$sql = "select sum(sum) from tables";
下们我们来看个实例,创建表代码如下:
- CREATE TABLE `cc`.`sumtable` (
- `id` INT( 4 ) NOT NULL ,
- `a1` INT( 4 ) NOT NULL ,
- `a2` INT( 4 ) NOT NULL ,
- `summ` INT( 8 ) NOT NULL
- ) ENGINE = InnoDB
插入记录,代码如下:
- INSERT INTO `cc`.`sumtable` (
- `id` ,
- `a1` ,
- `a2` ,
- `summ`
- )
- VALUES (
- '1', '5', '5', '0'
- ), (
- '2', '6', '5', '0'
- );
- */
-
-
- update sumtable set summ = a1+a2
-
-
- SELECT sum( summ ) FROM sumtable
- sum(summ)
- 21
|