Question

我有一张名为PayGrade的表，我的记录很少。我想显示不同的数据，但要根据具体的列

IF EXISTS(SELECT 1 FROM sys.tables WHERE object_id = OBJECT_ID('PayGrade'))
BEGIN;
    DROP TABLE [PayGrade];
END;
GO

CREATE TABLE [PayGrade] (
    [PayGradeID] INTEGER NOT NULL IDENTITY(1, 1),
    [ChangeDate] VARCHAR(255),
    [PayGrade] VARCHAR(255) NULL,
    [Pay] INTEGER NULL,
    PRIMARY KEY ([PayGradeID])
);
GO

INSERT INTO PayGrade([ChangeDate],[PayGrade],[Pay]) VALUES('2017-07-22 13:38:26','Grade 12','10000');
INSERT INTO PayGrade([ChangeDate],[PayGrade],[Pay]) VALUES('2018-01-31 02:33:02','Grade 12','10000');
INSERT INTO PayGrade([ChangeDate],[PayGrade],[Pay]) VALUES('2018-01-31 18:30:36','Grade 14','15000');

通过此查询，我得到了相应的输出。

SELECT DISTINCT ChangeDate, PayGrade, Pay
FROM PayGrade

输出：

Change Date         PayGrade    Pay
2017-07-22 13:38:26 Grade 12    10000
2018-01-31 02:33:02 Grade 12    10000
2018-01-31 18:30:36 Grade 14    15000

期望的输出：

Change Date         PayGrade    Pay
2017-07-22 13:38:26 Grade 12    10000
2018-01-31 18:30:36 Grade 14    15000

Answer 1

您可以使用Group By和Min功能执行此操作 -

SELECT MIN(ChangeDate) as ChangeDate, PayGrade, Pay
FROM PayGrade
GROUP BY PayGrade, Pay

Answer 2

您的预期输出似乎意味着您希望，对于一组给定的薪资等级和薪水，您需要第一个/最早的记录。如果是这样，那么我们可以使用行号如下：

SELECT
    [Change Date],
    PayGrade,
    Pay
FROM
(
    SELECT *,
        ROW_NUMBER() OVER (PARTITION BY PayGrade, Pay ORDER BY [Change Date]) rn
    FROM PayGrade
) t
WHERE rn = 1;

如何根据特定列显示不同的记录？

2 个答案: