在不同数据库环境下读取前N条记录数：

　　1. Oracle

　　Select * FROM TABLE1 Where ROWNUM<=N

　　2. Informix

　　Select FIRST N * FROM TABLE1 where 1=1

　　3. MySQL

　　Select * FROM TABLE1 where 1=1 LIMIT N

　　4. DB2

　　Select * ROW_NUMBER() OVER(ORDER BY COL1 DESC) AS ROWNUM Where ROWNUM<=N

　　或者

　　Select COLUMN FROM TABLE where 1=1 FETCH FIRST N ROWS ONLY

　　5.SQL Server

　　Select TOP N * FROM TABLE1 where 1=1

　　or

　　SET ROWCOUNT N Select * FROM TABLE1 where 1=1 SET ROWCOUNT N1

　　6. Sybase

　　SET ROWCOUNT N Select * FROM TABLE1 where 1=1 SET ROWCOUNT N1

　　7. FOXPRO

　　Select * TOP N FROM TABLE orDER BY COLUMN

　　8. Access

　　Select TOP N * FROM TABLE1 where 1=1