MySql
增删查改
关键词 | 描述 |
---|
SELECT | 查询 |
INSERT | 添加 |
UPDSTE | 修改 |
DELETE | 删除 |
一、MySql
查询
1、WHERE
条件
SELECT * FROM article WHERE `class` = 'PHP';
2、返回值
SELECT 字段1,字段2,字段3,字段4 FROM 表名 WHERE `字段名` = '条件';;
3、LIMIT
分页
SELECT 字段1,字段2,字段3,字段4 FROM 表名 WHERE `字段名` = '条件' LIMIT 2;
SELECT 字段1,字段2,字段3,字段4 FROM 表名 WHERE `字段名` = '条件' LIMIT 0, 2;
4、ORDER BY
排序语句
SELECT * FROM 表名 WHERE `字段名` = '条件' ORDER BY `字段名` DESC;
二、MySql
插入
INSERT INTO article (`字段名1`,`字段名2`,`字段名3`,`字段名4`,`字段名4`)VALUES('字段值1','字段值2','字段值3','字段值4','字段值5');
三、MySql
修改
UPDATE 表名 SET `字段名1`='字段值1', `字段名2`='字段值2' WHERE `字段名`='条件';
四、MySql
删除
DELETE FROM 表名 WHERE `字段名`='条件';
关键词 | 描述 |
---|
WHERE | 条件(查询、修改、删除) |
LIMIT | 分页(查询) |
ORDER BY | 排序(查询) |
五、主键
ALTER TABLE `表名`
ADD COLUMN `字段名` int(18) UNSIGNED NOT NULL AUTO_INCREMENT COMMENT '字段主键' FIRST ,
ADD PRIMARY KEY (`字段名`);
六、比较运算符
符号 | 描述 |
---|
= | 等号 |
<> | 不等于 |
> | 大于 |
< | 小于 |
>= | 大于等于 |
<= | 小于等于 |
# `=` 等号
SELECT * FROM `表名` WHERE `字段名` = '字段值';
# `<>` 不等于
SELECT * FROM `表名` WHERE `字段名` <> '字段值';
# `>` 大于
SELECT * FROM `表名` WHERE `字段名` > '字段值';
# `<` 小于
SELECT * FROM `表名` WHERE `字段名` < '字段值';
# `>=` 大于等于
SELECT * FROM `表名` WHERE `字段名` >= '字段值';
# `<=` 小于等于
SELECT * FROM `表名` WHERE `字段名` <= '字段值';
七、逻辑运算符
符号 | 描述 |
---|
NOT | 逻辑非,取反 |
AND | 逻辑与 |
OR | 逻辑或 |
XOR | 逻辑异或 |
# `NOT` 逻辑非
SELECT * FROM `表名` WHERE NOT(`字段名` = '字段值');
# `AND` 逻辑与
SELECT * FROM `表名` WHERE `字段名1` = '字段值1' AND `字段名2` = '字段值2';
# `OR` 逻辑或
SELECT * FROM `表名` WHERE `字段名1` = '字段值1' OR `字段名2` = '字段值2';
# `XOR` 逻辑异或
SELECT * FROM `表名` WHERE `字段名1` = '字段值1' XOR `字段名1` = '字段值1';
SELECT * FROM `表名` WHERE `字段名1` = '字段值1' XOR `字段名1` = '字段值2';
八、比较运算符
符号 | 描述 |
---|
BETWEEN | 在两值之间 |
NOT BETWEEN | 不在两值之间 |
IN | 在集合中 |
NOT IN | 不在集合中 |
LIKE | 模糊匹配 |
# `BETWEEN` 在两值之间
SELECT * FROM `表名` WHERE `字段名` BETWEEN '字段值1' AND '字段值2';
# `NOT BETWEEN` 不在两值之间
SELECT * FROM `表名` WHERE `字段名` NOT BETWEEN '字段值1' AND '字段值2';
# `IN` 在集合中
SELECT * FROM `表名` WHERE `字段名` IN ('字段值1','字段值2');
# `NOT IN`不在集合中
SELECT * FROM `表名` WHERE `字段名` NOT IN ('字段值1','字段值2');
# `LIKE` 模糊匹配
SELECT * FROM `表名` WHERE `字段名` LIKE '%字段值%';
SELECT * FROM `表名` WHERE `字段名` LIKE '%字段值_';