MySql從表結果集中隨機取一條數據

MySql從表結果集中隨機取一條數據  

[sql] 
Select * from (Select (@rowNo :=@rowNo+1) AS rowno, pwd from pur_admininfo, (Select @rowNo := 0) b) tmp where rowno=(Select Round(Rand() * 10000000 % (Select Count(*) from pur_admininfo))) limit 1;  

[sql] 
SELECT * FROM pur_admininfo AS t1 JOIN (SELECT ROUND(RAND() * ((SELECT MAX(rid) FROM pur_admininfo) - (SELECT MIN(rid) FROM pur_admininfo)) + (SELECT MIN(rid) FROM pur_admininfo)) AS rid) AS t2 WHERE t1.rid >= t2.rid ORDER BY t1.rid LIMIT 1;