SQL 如何在SQL中选择具有偶数ID号的列？
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How to select columns with an even ID number in SQL?
提问by Kurt Peek
I'm trying to solve the Hackerrank problem Weather Observation Station 3which is stated below:
我正在尝试解决 Hackerrank 问题Weather Observation Station 3，如下所述：
I came up with the following solution:
我想出了以下解决方案：
SELECT CITY
FROM STATION
WHERE MOD(ID, 2) = 0
but when I try to run it I get the compiler message "Wrong answer". I don't see what's wrong with this query?
但是当我尝试运行它时，我收到编译器消息“错误答案”。我不明白这个查询有什么问题？
回答by Ted
SELECT DISTINCT CITY
FROM STATION
WHERE MOD(ID, 2) = 0
回答by Vishal Prajapati
You can try this query:
你可以试试这个查询：
SELECT DISTINCT CITY FROM STATION WHERE (ID % 2) = 0
回答by Rajib Kumer Ghosh
For DB2:- SELECT DISTINCT CITY FROM STATION
对于 DB2：- SELECT DISTINCT CITY FROM STATION
WHERE MOD(ID, 2) = 0;
哪里 MOD(ID, 2) = 0;
For Oracle:- SELECT DISTINCT CITY FROM STATION
对于 Oracle：- 从车站中选择不同的城市
WHERE MOD(ID, 2) = 0;
哪里 MOD(ID, 2) = 0;
For MySQL:- SELECT DISTINCT CITY FROM STATION WHERE MOD(ID, 2) = 0; -- Or -- SELECT DISTINCT CITY FROM STATION
对于 MySQL：- SELECT DISTINCT CITY FROM STATION WHERE MOD(ID, 2) = 0; -- 或 -- 从车站选择不同城市
WHERE ID%2=0;
其中 ID%2=0;
For MSSQL:- SELECT DISTINCT CITY FROM STATION
对于 MSSQL：- SELECT DISTINCT CITY FROM STATION
WHERE ID%2=0;
其中 ID%2=0;
回答by Claire Hu
SELECT distinct CITY FROM STATION
WHERE MOD(ID,2)=0;
回答by Piyush Upadhyay
MYSQL:
MYSQL：
SELECT DISTINCT CITY FROM STATION WHERE (ID % 2)=0;
ORACLE:
甲骨文：
SELECT DISTINCT CITY FROM STATION WHERE MOD(ID, 2)=0;
回答by Gouru Sai
SELECT UNIQUE CITY FROM STATION WHERE MOD(ID,2)=0;
从车站选择唯一城市，其中 MOD(ID,2)=0;
回答by Hassiba Mouncet
I suggest another solution:
我建议另一种解决方案：
SELECT DISTINCT CITY
FROM STATION
WHERE ID LIKE '%0' OR ID LIKE '%2' OR ID LIKE '%4' OR ID LIKE '%6' OR ID LIKE '%8';
回答by Hassiba Mouncet
SELECT DISTINCT CITY FROM STATION WHERE (ID % 2) = 0;
从车站选择 DISTINCT CITY WHERE (ID % 2) = 0;
Distinct for not allowing Duplicates, (Id % 2) tells SQL to divide the Id by 2 and return the remainder. Since we're looking for only even values we set this to "= 0", as 2%2=0, 4%2=0, etc. If we were looking for odd-numbered Ids, we'd use "= 1" instead, since there's always a remainder of 1 when dividing odd numbers by 2. Hope this helps!
区别于不允许重复，(Id % 2) 告诉 SQL 将 Id 除以 2 并返回余数。由于我们只查找偶数值，因此我们将其设置为“= 0”，如 2%2=0、4%2=0 等。如果我们要查找奇数 ID，我们将使用“= 1” " 相反，因为在将奇数除以 2 时总是有 1 的余数。希望这会有所帮助！
回答by Karim Khayloufi
in MySql, you can do :
在 MySql 中，你可以这样做：
SELECT DISTINCT CITY FROM STATION WHERE (ID % 2)=0 ORDER BY CITY ;
回答by Subarata Talukder
If the question would like "Query a list of CITY names from STATION with even ID numbers only" then the answer would be
如果问题是“仅使用偶数 ID 号从 STATION 查询城市名称列表”，那么答案将是
select CITY from station where ID % 2 = 0;
But due the further criteria like "But must exclude duplicates from your answer." your answer should be
但是由于诸如“但必须从您的答案中排除重复项”之类的进一步标准。你的答案应该是
select DISTINCT CITY from station where ID % 2 = 0;
