SQL相关

查 SELECT * FROM where 限定搜索范围 = 等于
<> 不等于

大于
< 小于
= 大于等于
<= 小于等于
BETWEEN 在某个范围内
LIKE 搜索某种模式 % 模糊搜索
SELECT * FROM Persons WHERE City LIKE 'N%' 以N开头，后面的字母模糊搜索
SELECT * FROM Persons WHERE City LIKE '%g' 以g结尾
SELECT * FROM Persons WHERE City LIKE '%lon%' 含有lon

and 即条件交集
or 即条件并集

改 Update set where UPDATE 表 SET 列 WHERE
UPDATE Person SET FirstName = 'Fred' WHERE LastName = 'Wilson'
UPDATE Person SET Address = 'Zhongshan 23', City = 'Nanjing' WHERE LastName = 'Wilson'

删 DELETE from where DELETE FROM 表名称 WHERE 列名称 = 值
DELETE FROM Person WHERE LastName = 'Wilson'
增 INSERT INTO INSERT INTO table_name (列1, 列2,...) VALUES (值1, 值2,....)
INSERT INTO Persons VALUES ('Gates', 'Bill', 'Xuanwumen 10', 'Beijing')
INSERT INTO Persons (LastName, Address) VALUES ('Wilson', 'Champs-Elysees‘）

和 sum() SELECT SUM(column_name) FROM table_name
求绝对值 abs()