花了点时间整理了一下，取一表前N条记录，各个数据库的SQL写法：
1. ORACLE
SELECT * FROM TABLE1 WHERE ROWNUM<=N
2. INFORMIX
SELECT FIRST N * FROM TABLE1
3. DB2
SELECT * ROW_NUMBER() OVER(ORDER BY COL1 DESC) AS ROWNUM WHERE ROWNUM<=N
DB2
SELECT COLUMN FROM TABLE FETCH FIRST N ROWS ONLY
4. SQL SERVER
SELECT TOP N * FROM TABLE1
5. SYBASE
SELECT TOP N * FROM TABLE1
6. mysql:
select * from table_name limit N