Question

我有一个名为Order的表 -

这给了我一栏 -

 select min(OrderDate) from "order"

但是我想查看该记录的所有列。

任何帮助表示赞赏，

由于

Answer 1

 SELECT *
 from [order]
 WHERE OrderDate = (SELECT min(OrderDate) from [order])

Answer 2

使用order by沙top：

select top 1 o.*
from orders o
order by orderdate asc;

编辑：

如果您想要重复，请使用with ties：

select top 1 with ties o.*
from orders o
order by orderdate asc;

Answer 3

虽然M. Ali's answer准确无误，但根据表的大小和索引配置，可能会导致性能下降。它需要通过表格进行两次读取。

在SQL Server 2005及更高版本中，您可以使用窗口函数并将计划限制为通过表的单个读取。对于非常小的数据集，查询成本实际上更高，但读取次数减半。对于大型数据集，这应该会产生明显优越的性能。

代码示例：

SET NOCOUNT ON;

-- Populate Test Data

DECLARE @Orders TABLE (OrderNum int IDENTITY, OrderDate datetime);
INSERT INTO @Orders (OrderDate) VALUES ('2015-04-04');
INSERT INTO @Orders (OrderDate) VALUES ('2015-04-04');
INSERT INTO @Orders (OrderDate) VALUES ('2015-04-04');
INSERT INTO @Orders (OrderDate) VALUES ('2015-04-05');
INSERT INTO @Orders (OrderDate) VALUES ('2015-04-05');
INSERT INTO @Orders (OrderDate) VALUES ('2015-04-06');
INSERT INTO @Orders (OrderDate) VALUES ('2015-04-07');
INSERT INTO @Orders (OrderDate) VALUES ('2015-04-07');

-- Run Tests

SET STATISTICS IO ON;

PRINT 'Full Table';
SELECT * FROM @Orders;

PRINT 'Results using MIN';
SELECT      *
FROM        @Orders
WHERE       OrderDate = (SELECT min(OrderDate) FROM @Orders);

PRINT 'Results using RANK';
WITH BaseData AS
(
    SELECT
        *,
        RANK() OVER (ORDER BY OrderDate) AS OrderDateRank
    FROM        @Orders
)
SELECT      *
FROM        BaseData
WHERE       OrderDateRank = 1;

SET STATISTICS IO OFF;

SET NOCOUNT OFF;

查询费用：

MIN： 0.0065718

RANK： 0.014645

统计：

Full Table
Table '#1E0C7C2B'. Scan count 1, logical reads 1, physical reads 0, read-ahead reads 0, lob logical reads 0, lob physical reads 0, lob read-ahead reads 0.
Results using MIN
Table '#1E0C7C2B'. Scan count 2, logical reads 2, physical reads 0, read-ahead reads 0, lob logical reads 0, lob physical reads 0, lob read-ahead reads 0.
Results using RANK
Table '#1E0C7C2B'. Scan count 1, logical reads 1, physical reads 0, read-ahead reads 0, lob logical reads 0, lob physical reads 0, lob read-ahead reads 0.

选择最旧记录中的所有行

3 个答案: