SQL FIRST()
FIRST() 函数
FIRST() 函数返回指定的列中第一个记录的值。
SQL FIRST() 语法
SELECT FIRST(column_name) FROM table_name;
注释：只有 MS Access 支持 FIRST() 函数。
SQL Server、MySQL 和 Oracle 中的 SQL FIRST() 工作区
SQL Server 语法
SELECT TOP 1 column_name
FROM table_name
ORDER BY column_name ASC;
ORDER BY column_name ASC;
实例
SELECT TOP 1 name FROM Websites
ORDER BY id ASC;
ORDER BY id ASC;
MySQL 语法
SELECT column_name FROM table_name
ORDER BY column_name ASC
LIMIT 1;
ORDER BY column_name ASC
LIMIT 1;
实例
SELECT name FROM Websites
ORDER BY id ASC
LIMIT 1;
ORDER BY id ASC
LIMIT 1;
Oracle 语法
SELECT column_name FROM table_name
ORDER BY column_name ASC
WHERE ROWNUM <=1;
ORDER BY column_name ASC
WHERE ROWNUM <=1;
实例
SELECT name FROM Websites
ORDER BY id ASC
WHERE ROWNUM <=1;
ORDER BY id ASC
WHERE ROWNUM <=1;
演示数据库
在本教程中，我们将使用 JSON 样本数据库。
下面是选自 "Websites" 表的数据：
+----+--------------+---------------------------+-------+---------+ | id | name | url | alexa | country | +----+--------------+---------------------------+-------+---------+ | 1 | Google | https://www.google.cm/ | 1 | USA | | 2 | 淘宝 | https://www.taobao.com/ | 13 | CN | | 3 | 小白教程 | http://www.json.cn | 888 | CN | | 4 | 微博 | http://weibo.com/ | 20 | CN | | 5 | Facebook | https://www.facebook.com/ | 3 | USA | | 6 | 百度 | https://www.baidu.com/ | 4 | CN | | 7 | stackoverflow | http://stackoverflow.com/ | 0 | IND | +----+---------------+---------------------------+-------+---------+
SQL FIRST() 实例
下面的 SQL 语句选取 "Websites" 表的 "name" 列中第一个记录的值：
实例
SELECT name AS FirstSite FROM Websites LIMIT 1;
执行以上 SQL 结果如下所示：
