sql-server - SQL SERVER - 选择不同的随机行数

Question

我有以下查询，它选择 100 个随机行。但是我还需要选择不同的名称。我尝试过使用SELECT DISTINCT u.name和使用，GROUP BY u.name但无法使任何工作。

SELECT TOP (100) c.id, u.id u.name, b.sector, u.default
FROM cads AS c 
INNER JOIN users AS u ON c.cad = u.id 
INNER JOIN business AS b ON u.id = b.cad
WHERE (c.[public] = 'True') AND (c.valid = 'True') 
        AND (u.default = '$curr') 
        AND (c.expires IS NULL OR c.expires >= GETDATE()) 
ORDER BY NEWID() 

非常感谢

Answer 1

你可以通过巧妙地使用来做到这一点ROW_NUMBER()：

;With Arbitrary AS (
SELECT c.id, u.id u.name, b.sector, u.default,
    ROW_NUMBER() OVER (PARTITION BY u.name ORDER BY newid()) as rn
FROM cads AS c 
INNER JOIN users AS u ON c.cad = u.id 
INNER JOIN business AS b ON u.id = b.cad
WHERE (c.[public] = 'True') AND (c.valid = 'True') 
        AND (u.default = '$curr') 
        AND (c.expires IS NULL OR c.expires >= GETDATE()) 
)
select top 100 * from Arbitrary ORDER BY newid()

（您确实需要这两个ORDER BY子句，因为不能保证 CTE 中的内部子句实际上会影响TOP运算符正在考虑的行的顺序）

Answer 2

也许

SELECT TOP (100) min(c.id), u.id, u.name, min(b.sector), min(u.default)
FROM cads AS c 
INNER JOIN users AS u ON c.cad = u.id 
INNER JOIN business AS b ON u.id = b.cad
WHERE (c.[public] = 'True') AND (c.valid = 'True') 
        AND (u.default = '$curr') 
        AND (c.expires IS NULL OR c.expires >= GETDATE())
GROUP BY u.id, u.name 
ORDER BY NEWID()