解释:
官方解释:
语法:
LIMIT子句的SELECT语句的基本语法如下:
SELECT column1, column2, columnN
FROM table_name
LIMIT [no of rows]
以下是LIMIT子句时使用OFFSET子句的语法:
SELECT column1, column2, columnN
FROM table_name
LIMIT [no of rows] OFFSET [row num]
LIMIT,OFFSET允许只检索部分查询所产生的行。
示例:
有如下记录:
select * from COMPANY;
id | name | age | address | salary
----+-------+-----+-----------+--------
| Paul | 32 | California| 20000
| Allen | 25 | Texas | 15000
| Teddy | 23 | Norway | 20000
| Mark | 25 | Rich-Mond | 65000
| David | 27 | Texas | 85000
| Kim | 22 | South-Hall| 45000
| James | 24 | Houston | 10000
(7 rows)
下面是一个例子,这限制了表中的一行,根据从表中读取想要的行: yiibai.com
testdb=# SELECT * FROM COMPANY LIMIT 4;
这将产生以下结果:
id | name | age | address | salary
----+-------+-----+-------------+--------
| Paul | 32 | California | 20000
| Allen | 25 | Texas | 15000
| Teddy | 23 | Norway | 20000
| Mark | 25 | Rich-Mond | 650
(4 rows)
但在某些情况下,可能要选出一组记录从一个特定的偏移。下面是一个例子,从第三位开始取出3条:
testdb=# SELECT * FROM COMPANY LIMIT 3 OFFSET 2;
这将产生以下结果:
id | name | age | address | salary
----+-------+-----+-----------+--------
| Teddy | 23 | Norway | 20000
| Mark | 25 | Rich-Mond | 65000
| David | 27 | Texas | 85000
(3 rows)
SQL各关键字执行顺序:
SELECT DISTINCT <select_list>
FROM <left_table>
<join_type> JOIN <right_table>
ON <join_condition>
WHERE <where_condition>
GROUP BY <grout_by_list>
WITH {CUTE|ROLLUP}
HAVING <having_condition>
ORDER BY <order_by_list>
LIMIT <limit_number>