将SQL Server查询转换为MySQL [英] Convert SQL Server query to MySQL

问题描述

可能重复:
为数字选择TOP X(或最低)百分比MySQL中的值

Possible Duplicate:
Select TOP X (or bottom) percent for numeric values in MySQL

我该如何在MySQL中编写此查询?

How would I write this query in MySQL??

SELECT TOP 50 PERCENT * FROM Persons

表中的条目数将不断变化，因此我需要按百分比而不是固定数进行选择.

The number of entries in the table will be constantly changing so I need to select by percentage rather than a fixed number.

推荐答案

这实际上是

This is actually a duplicate question, but I now have a better, single-pass, fast, answer:

SELECT *
FROM
(
    SELECT tbl.*, @counter := @counter +1 counter
    FROM (select @counter:=0) initvar, tbl
    ORDER BY ordcolumn
) X
WHERE counter <= (50/100 * @counter)
ORDER BY ordcolumn;

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