Question

我有一个像这样的表测试：

real_id    name   active
1           A       0
2           B       1
3           C       1
4           D       1
5           E       0
6           F       1

我要找的是：

选择有效列= 1的行，最后只从中获取一个随机

我试过了：

/*get the max count from recordset*/
SET @rows_count = (SELECT COUNT(*) FROM test WHERE active = 1);
set @fakeId = 0;

SELECT * FROM test, (
    SELECT *, @fakeId := @fakeId + 1 AS fake_id,  
    (ROUND((RAND() * (@rows_count-1))+1)) AS random_nr
    FROM test
    WHERE active = 1
) AS total
WHERE total.fake_id = total.random_nr;
LIMIT 1;

乍一看它似乎运作良好，但如果我尝试过几次，我不时没有结果

解决

我通过计算select到变量

之外的random_nr来解决它们

SET @random_nr = (ROUND((RAND() * (@rows_count-1))+1));

在WHERE子句中

WHERE total.fake_id = @random_nr;

Answer 1

select * from test where active = 1 order by rand() limit 1

mysql从结果中随机选择

1 个答案: