嵌套SELECT语句也叫子查询,形如:
SELECT name FROM bbc WHERE region = (SELECT region FROM bbc WHERE name = 'Brazil')一个 SELECT 语句的查询结果可以作为另一个语句的输入值。上面的SQL语句作用为获得和'Brazil'(巴西)同属一个地区的所有国家。
SELECT name FROM bbc WHERE region IN (SELECT region FROM bbc WHERE name = 'Brazil')OK,
一、给出人口多于Russia(俄国)的国家名称 SELECT name FROM bbc WHERE population> (SELECT population FROM bbc WHERE name='Russia')
二、给出'India'(印度), 'Iran'(伊朗)所在地区的所有国家的所有信息 SELECT * FROM bbc WHERE region IN (SELECT region FROM bbc WHERE name IN ('India','Iran'))
三、给出人均GDP超过'United Kingdom'(英国)的欧洲国家. SELECT name FROM bbc WHERE region='Europe' AND gdp/population > (SELECT gdp/population FROM bbc WHERE name='United Kingdom')