查询以获取总行数和不同行之间的差异

I'm new to SQL, wasn't able to write the correct SQL. Given a table STATION that holds data for five fields namely ID, CITY, STATE, NORTHERN LATITUDE and WESTERN LONGITUDE.

我是SQL的新手，无法编写正确的SQL。给定一个表STATION，其中包含五个字段的数据，即ID，CITY，STATE，NORTHERN LATITUDE和WESTERN LONGITUDE。

+-------------+------------+
| Field       |   Type     |
+-------------+------------+
| ID          | INTEGER    |
| CITY        | VARCHAR(21)|
| STATE       | VARCHAR(2) |
| LAT_N       | NUMERIC    |
| LONG_W      | NUMERIC    |
+-------------+------------+

Let NUM be the number of cities and NUMunique be the number of unique cities, then write a query to print the value of NUM - NUMunique.

设NUM为城市数，NUMunique为唯一城市数，然后编写查询以打印NUM - NUMunique的值。

I tried:

我试过了：

select (count(CITY)- distinct count(CITY)) from STATION;

3 个解决方案

#1

You can use the select distinct inside the count and try this way

您可以在计数内使用select distinct并尝试这种方式

select  (count(CITY)- count(distinct CITY)) from STATION;

#2

SELECT COUNT(CITY) - COUNT(DISTINCT CITY) AS N FROM STATION

SELECT COUNT（CITY） - COUNT（DISTINCT CITY）作为N FROM FROM STATION

#3

-1

SELECT (COUNT(CITY)- COUNT(DISTINCT(CITY))) AS diff
FROM STATION

#1