sql server 怎么查询前n条数据

Answer 1

1. Oracle数据库

SELECT * FROM TABLENAME WHERE ROWNUM <= N

2. Infomix数据库

SELECT FIRST N * FROM TABLENAME

3. DB2数据库

SELECT *
FROM (SELECT * ROW_NUMBER() OVER({ORDER BY COL1 DESC}) AS ROWNUM FROM TABLENAME)
WHERE ROWNUM <= N
或者
SELECT COLUMN FROM TABLENAME FETCH FIRST N ROWS ONLY

4. SQL Server数据库

SELECT TOP N * FROM TABLENAME

5. Sybase数据库

SET ROWCOUNT N
GO
SELECT * FROM TABLENAME

6. MySQL数据库

SELECT * FROM TABLENAME LIMIT N

7. FoxPro数据库

SELECT * TOP N FROM TABLENAME ORDER BY COLUMN

以下示例从表 [tableName] 中读取符合查询条件的前10条记录的SQL语句

1.Access

select top (10) * from [tableName] where [query condition]

1.1 带order by的查询限制
Access中对select top的语句支持有限，如果要在查询top语句的后面使用order by，则order by排序字段必须是无重复值，如果有重复值的话，那么这个TOP很可能会失效，会返回所有记录。
解决办法：在order by 最后面加入主键id,如：
select top 10 from [tableName] order by 排序字段1,id

1.2 带子查询的示例
假如id是表[tableName]的主键，以下语句期望返回三条记录，但结果返回4条记录
select top 3 * from [tableName] where id in(是个子查询，结果比如为1,2,3,4)
解决办法
select top 3 * from [tableName] where id in(是个子查询，结果比如为1,2,3,4) order by id

2 DB2

select column from [tableName] where [query condition] fetch first 10 rows only
3 MySQL

select * from [tableName] where [query condition] limit 10
4 SQL Server

4.1 读取前10条
select top (10) * from [tableName] where [query condition]

4.2 读取后10条
select top (10) * from [tableName] order by id desc

4.3 按照某个排序，第5到10这几个记录
select top 6 * from [tableName] where id not in(select top 4 id from [tableName])

5 Oracle

select * from [tableName] where rownum<=10

Answer 2

select top n * from tbl