关系型数据库最常用的SQL语句（增删改查）

一、增添数据

格式：INSERT INTO table_name VALUES(value1,value2,...);

二、删除数据

格式：DELETE FROM table_name WHERE clause;

三、修改数据

格式：UPDATE table_name SET field1 = new_value1,field2 = new_value2,...WHERE clause;

四、查询数据

格式：SELECT t.filed/t.* FROM table_name t WHERE clause;

1、COUNT SUM MAX MIN AVG(filed)

2、DISTINCT field

3、field = > >= < <= != value

4、field IS NULL

5、field LIKE '%_'

6、AND OR NOT

7、field BETWEEN para1 AND para2

8、field IN(value1,value2,...)

9、GROUP BY field

10、HAVING clause

11、ORDER BY field ASC/DESC

五、嵌套查询

格式：SELECT * FROM table_name1 a WHERE a.field =/IN (SELECT b.field FROM table_name2 b WHERE clause);

六、连接查询

格式：SELECT a.filed/*,b.filed/* FROM table_name1 a,table_name2 b WHERE clause;

1、内连接

格式：SELECT a.filed/*,b.filed/* FROM table_name1 a INNER JOIN table_name2 b ON clause;

2、左连接

格式：SELECT a.filed/*,b.filed/* FROM table_name1 a LEFT JOIN table_name2 b ON clause;

3、右连接

格式：SELECT a.filed/*,b.filed/* FROM table_name1 a RIGHT JOIN table_name2 b ON clause;

4、全连接

格式：SELECT a.filed/*,b.filed/* FROM table_name1 a FULL JOIN table_name2 b ON clause;