找到多列重复mysql

Question

如何找到多列的重复记录？表具有主键（自动增量）

EG

 ID  a_id  b_id
 ---- ---- ------
   1    34   23
   2    34   23
   3    35   25

例如，我想找到具有相同a_id和b_id ...

的记录

由于

Answer 1

select t.ID, t.a_id, t.b_id
from (
  select a_id, b_id
  from tbl
  group by a_id, b_id
  having count(*) > 1) x, tbl t
where x.a_id = t.a_id and x.b_id = t.b_id
order by t.a_id, t.b_id

此查询将显示元组上的所有重复项（a_id，b_id）

Answer 2

SELECT r1.id, r2.id
FROM test r1, test r2
WHERE r1.id < r2.id
AND r1.a_id = r2.a_id
AND r1.b_id = r2.b_id

Answer 3

修改

误读了你要找的东西。您可以使用group by参数在表中找到重复的条目，如上所述进行选择，甚至是自联接。

mysql> SELECT * FROM my_table;
+------+------+------+
| ID   | a_id | b_id |
+------+------+------+
|    1 |   34 |   23 |
|    2 |   34 |   23 |
|    3 |   35 |   25 |
+------+------+------+
3 rows in set (0.00 sec)

mysql> SELECT t1.ID source_row, 
    ->        t2.ID same_as_row, 
    ->        t1.a_id a_id, 
    ->        t1.b_id b_id 
    ->   FROM my_table t1 
    ->   JOIN my_table t2 
    ->     ON t1.a_id = t2.a_id 
    ->    AND t1.b_id = t2.b_id 
    ->    AND t1.ID != t2.ID;

+------------+-------------+------+------+
| source_row | same_as_row | a_id | b_id |
+------------+-------------+------+------+
|          2 |           1 |   34 |   23 |
|          1 |           2 |   34 |   23 |
+------------+-------------+------+------+
2 rows in set (0.00 sec)

<强> EDIT2：

mysql> SELECT * FROM my_table;
+------+------+------+
| ID   | a_id | b_id |
+------+------+------+
|    1 |   34 |   23 | # same as 2, 4
|    2 |   34 |   23 | # same as 1, 4
|    3 |   35 |   25 |
|    4 |   34 |   23 | # same as 1, 2
|    5 |   31 |   23 |
+------+------+------+

mysql>   SELECT t1.ID source_row, 
    ->          t2.ID same_as_row, 
    ->          t1.a_id a_id, 
    ->          t1.b_id b_id 
    ->     FROM my_table t1 
    ->     JOIN my_table t2 
    ->       ON t1.a_id = t2.a_id 
    ->      AND t1.b_id = t2.b_id 
    ->      AND t1.ID != t2.ID
    -> ORDER BY source_row;
+------------+-------------+------+------+
| source_row | same_as_row | a_id | b_id |
+------------+-------------+------+------+
|          1 |           2 |   34 |   23 |
|          1 |           4 |   34 |   23 |
|          2 |           1 |   34 |   23 |
|          2 |           4 |   34 |   23 |
|          4 |           1 |   34 |   23 |
|          4 |           2 |   34 |   23 |
+------------+-------------+------+------+
6 rows in set (0.00 sec)

Answer 4

这是一个基本的SQL查询：

SELECT *
FROM my_table
WHERE a_id = b_id;

其中my_table是您的表名。