如何SQL查询与条件不同

Question

简单的数据库：

street  | age 
1st st  | 2 
2nd st  | 3 
3rd st  | 4 
3rd st  | 2 

我想建立一个查询，将返回DISTINCT街道名称，但只适用于那些家庭中，没有一个是超过3

，这样的结果将是：

street  | age 
    1st st  | 2 
    2nd st  | 3 

我该怎么办呢？我知道DISTINCT，但现在如何实现条件为所有符合DISTINCT

Answer 1

假设表格的名称是'tab'。然后，您可以尝试：

select distinct street from tab where street not in (select street from tab where age>3); 

我创建了一个SQL小提琴在这里你可以查看结果： http://sqlfiddle.com/#!9/2c513d/2

Answer 2

鲜明的街头户名称的记录，其中没有一个是超过3：

SELECT street 
FROM table 
GROUP BY street 
HAVING COUNT(1) <= 3 

Answer 3

使用GROUP BY

Select Street 
from yourtable 
group by street 
Having sum(age)<=3 

另一种方式可以使用NOT EXISTS

SELECT * 
FROM yourtable a 
WHERE NOT EXISTS 
    (SELECT street 
    FROM yourtable b 
    WHERE age > 3 
     AND a.street = b.street) 

Answer 4

SELECT DISTINCT street 
FROM table 
WHERE NOT(age>3)