oracle隨機(jī)選擇100條數(shù)據(jù) sql隨機(jī)抽取幾條數(shù)據(jù)的方法,推薦?
sql隨機(jī)抽取幾條數(shù)據(jù)的方法,推薦?四種數(shù)據(jù)庫隨機(jī)獲取10條數(shù)據(jù)的方法SQL Server:SELECT TOP 10 * FROM T_USER ORDER BY NEWID()ORACLE:SEL
sql隨機(jī)抽取幾條數(shù)據(jù)的方法,推薦?
四種數(shù)據(jù)庫隨機(jī)獲取10條數(shù)據(jù)的方法
SQL Server:
SELECT TOP 10 * FROM T_USER ORDER BY NEWID()
ORACLE:
SELECT * FROM (SELECT * FROM T_USER ORDER BY DBMS_RANDOM.RANDOM()) WHERE RONUM <= 10
MySQL:
SELECT * FROM T_USER ORDER BY RAND() LIMIT 10
Access:
SELECT TOP 10 * FROM T_USER ORDER BY rnd([一個自動編號字段])
這條語句在 Access 中的“查詢”中是可以運(yùn)行并得到隨機(jī)結(jié)果的,但在 ASP.NET等后臺程序代碼中卻無法得到預(yù)期的隨機(jī)效果。
正確的寫法如下:
以ASP.NET為例:
Random random = new Random(System.Guid.NewGuid().GetHashCode())
int r = random.Next()
string sql = "SELECT TOP 10 * FROM T_USER ORDER BY RND(" (-r) "*自動編號字段)"