SQL基础(1)

TB_NAME：表名；COLUMN：字段，列名；code：条件；

查询语句：select；

(1)SELECT * FROM TB_NAME;

(2)SELECT COLUMN FROM TB_NAME;

(3)SELECT COLUMN FROM TB_NAME WHERE COLUMN1=.. AND/OR COLUMN2=..;

(4)SELECT COLUMN FROM TB_NAME WHERE (COLUMN1=..AND/OR COLUMN2=..) OR/AND COLUMN3=..;

DML（data manipulation language）语句：insert ，delete，update；

对数据进行操作。

INSERT:

(1)INSERT INTO TB_NAME(COLUMN1，COLUMN2,)

VALUES(.. , ..);

(2)INSERT INTO TB_NAME(COLUMN1，COLUMN2,)

VALUES(.. , ..),(.. , ..)...;

没有的COLUMN一般默认为null；

 DELETE:

(1) DELETE FROM TB_NAME;

(2)DELETE FROM TB_NAME WHERE code1;

(3)DELETE FROM TB_NAME WHERE code1 AND/OR code2;

UPDATE:

(1)UPDATE TB_NAME SET COLUMN1=VALUE1;

(2)UPDATE TB_NAME SET COLUMN1=VALUE1, COLUMN2=VALUE2...;

(3)UPDATE TB_NAME SET COLUMN1=VALUE1 WHERE code1;

(4)UPDATE TB_NAME SET COLUMN1=VALUE1, COLUMN2=VALUE2... WHERE code1 AND/OR code2;