查询重复值的两个表

Question

我有一个存储过程，可以将记录从一个表移动到另一个表。但是，我现在想要创建一个过程来检查'TableA'中的数据与'TableB'中的数据

SELECT A.Num, B.Num
FROM TableA AS A 
LEFT JOIN TableB AS B ON A.Num = B.Num
WHERE B.Num IS NULL

基本上，我想提取任何不在'TableB'但是在'TableA'中的数字，这是一种LEFT JOIN方式吗？到目前为止，我找不到丢失的文件是不成功的，我已经删除了一些以形成测试用例。

Answer 1

您可以使用not exists

SELECT  *   
FROM TableA A  
WHERE NOT EXISTS (SELECT *      
                  FROM TableB B
                  WHERE A.NUM = B.NUM);

或not in：

SELECT  *   
FROM TableA A  
WHERE A.NUM not in (SELECT B.NUM
                  FROM TableB B);

Answer 2

SELECT Num from TableA
EXCEPT
SELECT Num from TableB

Answer 3

select * from tableA
where id not in (select id from tableB)

或

select * from tableA a
left join tableB b on a.id = b.id
where b.id is null

Answer 4

查找两个表之间的重复项

select table1.column_name, count(*) from table_name table1
inner join table_name table2
ON table1.coumn_name = table2.column_name;

前任：

SELECT u.username  FROM users u
INNER JOIN src_users ud
ON u.username = ud.username;

在单个表中查找重复项

select username, count(*) from users group by username having count(*) >1;

Answer 5

select * from tableA
where id in (select id from tableB);