Question

我有一个表，我想检查一列的所有值是否相同。

以下是我表格中的条目。

两栏

rid,value
(1,1)
(1,1)
(2,1)
(2,0)
(2,0)
(3,0)
(3,0)
(3,0)

我想查询哪个让我摆脱1，因为它的所有值都是1.所有记录对于rid 1都有值1而rid 2和3没有将所有值都作为1所以它们不应该被选中。

Answer 1

使用group by和having可以得到你想要的东西：

    SELECT rid, value
    FROM my_table
    GROUP BY rid
    HAVING COUNT( distinct value) = 1

<强>更新

根据评论，过滤该值将得到结果：

SELECT *
FROM
    (
    SELECT rid, value
    FROM my_table
    GROUP BY rid
    HAVING COUNT( distinct value) = 1 
    ) AS T1
WHERE value = 1

如果值只有1或0，那么你可以做到这一点：

    SELECT rid, value
    FROM my_table
    GROUP BY rid
    HAVING COUNT( * ) = SUM(value)

Answer 2

你可以这样做：

  CREATE TABLE my_table (
  id varchar(255),
  col_value varchar(255)
);
INSERT INTO my_table 
  VALUES
         ('1','1'),
         ('1','1'),
         ('2','1'),
         ('2','1'),
         ('2','1'),
         ('2','4'),
         ('3','1'),
         ('3','1');

查询选择：

SELECT src.* FROM
(
    SELECT DISTINCT t1.* FROM my_table AS t1 
) AS src
WHERE src.id NOT IN(
        SELECT test.id
        FROM 
        (
             SELECT DISTINCT t1.* FROM my_table AS t1 
        ) AS test
        GROUP BY test.id
        HAVING COUNT(*) > 1
 )

fiddle此处。

从一个表中选择查询以检查列中是否存在相同的值，mysql选择查询

2 个答案: