Sql 通过比较两个表来提取缺少的行

e、 g

简化案例表：

select count(1) from table_a; --> returns 5 results
select count(1) from table_b; --> returns 4 results
select count(1) from table_a, table_b2 b 
where b.id_ab like a.id_ab; --> returns 4 results
select count(1) from table_a, table_b2 b 
where b.id_ab not like a.id_ab; --> returns unexpected result

SQL:

select count(1) from table_a; --> returns 5 results
select count(1) from table_b; --> returns 4 results
select count(1) from table_a, table_b2 b 
where b.id_ab like a.id_ab; --> returns 4 results
select count(1) from table_a, table_b2 b 
where b.id_ab not like a.id_ab; --> returns unexpected result

尝试此操作（除外），但遇到错误

select a.id_ab from table_a a, table_b b except select a.id_ab from table_a, table_b2 b 
where b.id_ab not like a.id_ab; 

或者如何使用union来实现这一点？e、 g

(Select * from table_a except select * from table_b) Union All (Select * from table_b     except select record_id from table_a);

预期结果：

多谢各位

使用下面的查询（添加了左外连接）

select a.id_ab 
from table_a a 
    LEFT JOIN table_b b on a.id_ab = b.id_ab 
where b.id_ab is null

它将获得表a中不匹配的数据

 select count(1) from table_a, table_b2 b 
 where b.id_ab(+) = a.id_ab;

如果只需要缺少行，请使用下面的查询

 select count(1) from table_a, table_b2 b 
 where b.id_ab <> a.id_ab;

但不像

  SELECT col1,col2 from table_a
   UNION
   SELECT col1 from table_b

使用下面的查询（添加了左外部联接）

它将获得表a中不匹配的数据

 select count(1) from table_a, table_b2 b 
 where b.id_ab(+) = a.id_ab;

如果只需要缺少行，请使用下面的查询

 select count(1) from table_a, table_b2 b 
 where b.id_ab <> a.id_ab;

但不像

  SELECT col1,col2 from table_a
   UNION
   SELECT col1 from table_b

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谢谢你的传奇。很好用。谢谢你的传奇。工作完美。