JAVA下的SQL_System的建立

SELECT   title_id, SUM(qty)
FROM     sales 
GROUP BY title_id
GO

SELECT   title_id, SUM(qty) AS "总销售"
FROM     sales
GROUP BY title_id
GO

SELECT   type, pub_id, AVG(price) AS "Average Price"
FROM     titles
GROUP BY type, pub_id
GO

SELECT   type, pub_id,AVG(price) AS "平均价格"
FROM     titles
WHERE    royalty = 15
GROUP BY ALL type, pub_id 
GO

下面的代码通过用HAVING来查找平均价格高于$10的书籍。
SELECT   type, pub_id, AVG(price) AS "平均价格"
FROM     titles
GROUP BY type, pub_id
HAVING   AVG(price) > 10.00
GO

用户还可以在语句中使用逻辑操作AND。
SELECT   type, pub_id, AVG(price) AS "平均价格"
FROM     titles
GROUP BY type, pub_id
HAVING   AVG(price) >= 10.00 AND
         AVG(price) <= 30.00
GO

用户可以使用BETWEEN子句，代替上面实例中的AND操作，代码如下：
SELECT   type, pub_id, AVG(price) AS "平均价格"
FROM     titles
GROUP BY type, pub_id
HAVING   AVG(price) BETWEEN 10.00 AND 20.00
GO

SELECT   SUM(price)
FROM     titles
WHERE    type = 'mod_cook'
HAVING   SUM(price) > 10
GO

SELECT   au_lname, au_fname
FROM     authors
ORDER BY au_lname ASC
GO

SELECT   job_id, lname, fname
FROM     employee
ORDER BY job_id, lname, fname
GO

用户可以在ORDER BY子句使用的同时，还可以使用GROUP BY子句：
SELECT   type, pub_id, AVG(price) AS "Average Price"
FROM     titles
GROUP BY type, pub_id
ORDER BY type
GO

用户还可以使用自定义的词组进行排序：
SELECT   type, pub_id, AVG(price) AS "平均价格"
FROM     titles
GROUP BY type, pub_id
ORDER BY '平均价格'
GO

SELECT   city, state
FROM     publishers
UNION    SELECT city, state
         FROM   stores
GO

用户可以的定义列的名称，代码如下：
SELECT   city AS "所有城市", state AS "所有地区" 
FROM     publishers
UNION    SELECT city, state
         FROM   stores
GO

如果通过同一个表查询，就不用再写一次SELECT语句：
SELECT   city, country
FROM     publishers
UNION    SELECT city, state
         FROM   stores
GO

用户还可以在查询语句时，使用GROUP BY 或者HAVING。
SELECT   type AS "类型" , COUNT(title) AS "标题个数" 
FROM     titles
GROUP BY type
UNION    SELECT   pub_name, COUNT(titles.title)
         FROM     publishers, titles
         WHERE    publishers.pub_id = titles.pub_id
         GROUP BY pub_name
GO

COUNT可以计算查询结果的个数：
SELECT   COUNT(*)
FROM     publishers
GO

AVG、COUNT、MAX、MIN和SUM 功能都可以使用ALL 和 DISTINCT操作。实例如下：
SELECT   MAX(price) - MIN(price) AS "价格差异"
FROM     titles
GO

在下面的实例中，SUM将计算总和：
SELECT   stores.stor_name, SUM(sales.qty) AS "全部项目排序" 
FROM     sales, stores
WHERE    sales.stor_id = stores.stor_id
GROUP BY stor_name
GO