增 INSERT
INSERT INTO <表> (字段, ...) VALUES(值, ...);
INSERT INTO user_table (username, password) VALUES('lisi', '111111');
删 DELETE
DELETE FROM <表> WHERE 条件;
DELETE FROM user_table WHERE ID=2;
改 UPDATE
UPDATE <表> SET 字段=新值,字段=新值,... WHERE 条件;
UPDATE user_table SET password='654321', username='blue2' WHERE ID=1;
查 SELECT
SELECT 字段列表 FROM <表> WHERE 条件 ORDER BY 字段 LIMIT 30,30;