1 --使用表达式更新一个单列的值
2 UPDATE employee
3 SET salary = salary*1.1
4 WHERE department_id = 90
5
6 --使用子查询更新一个单列的值
7 UPDATE employee
8 SET salary = (
9 SELECT employee2.salary
10 FROM employee2 WHERE employee_id = 10
11 )
12 WHERE employee_id = 90
13
14 --通过WHERE子句中使用子查询确定要更新的数据行来更新单列的值
15
16
17 --通过使用SELECT语句定义表及列的值来更新表
18 UPDATE (
19 SELECT col1,col2,...
20 FROM table_name1
21 WHERE ......
22 )
23 SET col_value = new_col_value
24
25 --通过子查询更新多列
26 UPDATE
27 SET (col1,col2) = (
28 SELECT col2,col2 FROM table1
29 )
30 WHERE ...
