SQL多表多字段比对方法实例代码_Mysql

SELECT T1.ID,T2.ID,T1.`NAME`,T2.`NAME`
FROM A T1
LEFT JOIN B T2
ON T1.ID = T2.ID
AND COALESCE(T1.ID,'') <> ''
AND COALESCE(T2.ID,'') <> ''
WHERE T1.`NAME` <> T2.`NAME`;

-- 写法01
SELECT COUNT(1) FROM (
SELECT DISTINCT ID,`NAME` FROM A
) T1;
-- 写法02
SELECT COUNT(1) FROM (
SELECT DISTINCT ID,`NAME` FROM B
) T2;
-- 写法03
SELECT COUNT(1) FROM (
SELECT DISTINCT ID,`NAME` FROM A
UNION
SELECT DISTINCT ID,`NAME` FROM B
) T0;

-- 写法01
SELECT T2.`NAME`,T2.* FROM A T2 WHERE  T2.`NAME` IS NOT NULL
AND NOT EXISTS (SELECT 1 FROM B T1 WHERE T1.ID = T2.ID);
-- 写法02
SELECT T2.`NAME`,T2.* FROM A T2 WHERE  T2.`NAME` IS NOT NULL
AND T2.ID NOT IN (SELECT T1.ID FROM B T1 );

SELECT ID,`NAME`,COUNT(*)
FROM A
GROUP BY ID
HAVING COUNT(`NAME`)>1;

SELECT ID, COUNT(DISTINCT `NAME`)
FROM A
GROUP BY ID
HAVING COUNT(DISTINCT `NAME`)>1;

-- 写法01
SELECT ID
FROM A
GROUP BY ID
HAVING COUNT(*)>1;
-- 写法02
SELECT ID,COUNT(ID)
FROM A
GROUP BY ID
HAVING COUNT(ID)>1;

SELECT ID,`NAME`
FROM A
GROUP BY ID,`NAME`
HAVING COUNT(*)>1
ORDER BY ID;

-- 建表
CREATE TABLE IF NOT EXISTS TEST01.A
(
     ID                      VARCHAR(50)               COMMENT 'ID号'       -- 01
    ,NUMS                    INT                       COMMENT '数字'       -- 02
    ,NAME                    VARCHAR(50)               COMMENT '名字'       -- 03

)
COMMENT 'A表'
STORED AS PARQUET
;

-- 插数
INSERT INTO TEST01.A (ID,NUMS,NAME) VALUES ('01',1,NULL);
INSERT INTO TEST01.A (ID,NUMS,NAME) VALUES ('02',2,'');
INSERT INTO TEST01.A (ID,NUMS,NAME) VALUES ('03',3,'c');

-- 删数
DELETE FROM TEST01.A WHERE ID = '04';
-- 删表
DROP TABLE IF EXISTS TEST01.A;