SELECT * FROM 表名 WHERE 字段名='符合条件'
INSERT INTO 表名(字段1, 字段2,。。。) VALUES(值1, 值2, 。。。)
UPDATE 表名 SET 字段1='值1',字段2='值3' WHERE 字段3='值3'
DELETE FROM 表名 WHERE 字段1='值1'
左联 SELECT * FROM A LEFT JOIN B ON A.xx=B.xx WHERE A.xx=''
SELECT * FROM 表名 WHERE 字段名='符合条件'
INSERT INTO 表名(字段1, 字段2,。。。) VALUES(值1, 值2, 。。。)
UPDATE 表名 SET 字段1='值1',字段2='值3' WHERE 字段3='值3'
DELETE FROM 表名 WHERE 字段1='值1'
左联 SELECT * FROM A LEFT JOIN B ON A.xx=B.xx WHERE A.xx=''