若何随机选取n条记录大概对记录作随机排序?[MSSQL防范]

A. 要得到随机排序的列,大概返回x条随机挑选的列,你可以利用随机数.但是RAND函数在一个查询中只能返回一个后果.你可以在NOWID函数返回的列上做ORDER BY.请看示例:

SELECT *
FROM Northwind..Orders
ORDER BY NEWID()

SELECT TOP 10 *
FROM Northwind..Orders
ORDER BY NEWID()

这段话翻译得真是吃力,干脆不管原文,直接意译了.
不过提醒大家注意,这种办法是要对整个表扫描,然后产生一个计算列再排序的,最好不要对大的表作这样的操作,不然会很慢的.

Q. How can I randomly sort query results?

A. To randomly order rows, or to return x number of randomly chosen rows, you can use the RAND function inside the SELECT statement. But the RAND function is resolved only once for the entire query, so every row will get same value. You can use an ORDER BY clause to sort the rows by the result from the NEWID function, as the following code shows:

SELECT *
FROM Northwind..Orders
ORDER BY NEWID()

SELECT TOP 10 *
FROM Northwind..Orders
ORDER BY NEWID()

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