SQL必知必会语法整理

常用SQL语句速查

1.ALTER TABLE
更新现有表的结构

ALTER TABLE tablename
(    
  ADD|DROP column datatype [NULL|NOT NUILL] [CONSTRAINTS],    
  ADD|DROP column datatype [NULL|NOT NUILL] [CONSTRAINTS],    
  ...
);

2.COMMIT
提交事务给DBMS

COMMIT [TRANSACTION];

3.CREATE INDEX
创建一个或多个索引

CREATE INDEX indexname
ON tablename (column, ...);

4.CREATE PROCEDURE
创建存储过程，Oracle语法有所不同

CREATE PROCEDURE procedurename [parameters] [options]
AS
SQL statement;

5.CREATE TABLE
建表

CREATE TABLE tablenmae
(
  column datatype [NULL|NOT NULL] [CONSTRAINTS],
  column datatype [NULL|NOT NULL] [CONSTRAINTS],
  ...
);

6.CREATE VIEW
创建视图

CREATE VIEW viewname AS
SELECT columns, ...
FROM tables, ...
[WHERE ...]
[GROUP BY ...]
[HAVING ...];

7.DELETE
从表中删除一行或多行，针对表数据

DELETE FROM tablename
[WHERE ...];

8.DROP
丢弃数据库对象，适用表，视图，存储过程etc

DROP INDEX|PROCEDURE|TABLE|VIEW
indexname|procedurename|tablename|viewname;

9.INSERT
向表中插入数据

INSERT INTO tablename [(columns, ...)]
VALUES(values, ...);

10.INSERT SELECT
输出重定向

INSERT INTO tablename [(columns, ...)]
SELECT columns, ... FROM tablename, ...
[WHERE ...];

11.ROLLBACK
事务回滚

ROLLBACK [TO savepointname];

或者：

ROLLBACK TRANSACTION;

12.SELECT
n表检索数据

SELECT columnnmae, ...
FROM tablename, ...
[WHERE ...]
[UNION ...]
[GROUP BY ...]
[HAVING ...]
[ORDER BY ...];

13.UPDATE
更新表中数据

UPDATE tablename
SET columnname = value, ...
[WHERE ...];

SQL数据类型

自拓展

详细讲解