Oracle取TOP N條記錄

在SQL Server裏面有top關鍵字可以很方便的取出前N條記錄，但是Oracle裏面卻沒有top的使用，類似實現取出前N條記錄的簡單方法如下：

方法1：利用ROW_NUMBER函數

取出前5條記錄：

SELECT NO FROM (
    SELECT ROW_NUMBER() OVER (ORDER BY NO) RNO, NO FROM ROWNUM_TEST
)WHERE RNO <= 5  ORDER BY NO ;

取出中間5條記錄：

SELECT NO FROM (
    SELECT ROW_NUMBER() OVER (ORDER BY NO) RNO, NO FROM ROWNUM_TEST
) WHERE RNO BETWEEN 5 AND 10 ORDER BY NO;

 

方法2：利用子查詢

取出前5條記錄：

SELECT NO FROM (
    SELECT NO FROM ROWNUM_TEST  ORDER BY NO
)WHERE ROWNUM <= 5  ORDER BY NO ;

取出中間5條記錄：

SELECT NO  FROM (
    SELECT NO, ROWNUM RNO FROM (
        SELECT NO FROM ROWNUM_TEST  ORDER BY NO
    )
) WHERE RNO BETWEEN 5 AND 10  ORDER BY NO;