【SQL每日一练】查询“OCCUPATIONS”中的“Occupation”列并按Doctor、Professor、Singer、Actor列输出

文章目录

• 题目
• 一、分析
• 二、题解
• • 1.SqlServer
  • 2.MySQL
  • 3.Oracle
• 总结

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题目

查询"OCCUPATIONS"中的"Occupation"列，使每个姓名按字母顺序排序，并显示在其相应的"职业》下方。输出列标题应分别为Doctor、Professor、Singer和Actor。

注意：当不再有与某个职业对应的名称时，打印NULL。
输入格式

职业表描述如下：

职业只包含以下值之一：博士、教授、歌手或演员。

样本输入

样本输出

Jenny    Ashley     Meera  Jane
Samantha Christeen  Priya  Julia
NULL     Ketty      NULL   Maria

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一、分析

以SqlServer为例:

1.输出列标题应分别为Doctor、Professor、Singer和Actor

可以使用Pivot把行转为列：Pivot (max(name) for Occupation in ([Doctor],[Professor],[Singer], [Actor])) as b

2、使每个姓名按字母顺序排序，通过窗口函数进行排序row_number() over(PARTITION by Occupation order by name)

二、题解

1.SqlServer

代码如下（示例）：

select Doctor,Professor,Singer, Actor from (select Occupation,Name, row_number() over(PARTITION by Occupation order by name)  rom
from OCCUPATIONS ) as a 
Pivot (max(name) for Occupation in ([Doctor],[Professor],[Singer], [Actor])) as b

2.MySQL

代码如下（示例）：

SELECT MAX(C1), MAX(C2), MAX(C3), MAX(C4) FROM
(SELECT
COUNT(*) Rank,
IF (STRCMP(T1.Occupation, 'Doctor') = 0, T1.Name, NULL) AS C1,
IF (STRCMP(T1.Occupation, 'Professor') = 0, T1.Name, NULL) AS C2,
IF (STRCMP(T1.Occupation, 'Singer') = 0, T1.Name, NULL) AS C3,
IF (STRCMP(T1.Occupation, 'Actor ') = 0, T1.Name, NULL) AS C4
FROM Occupations T1 LEFT JOIN Occupations T2 ON T1.Occupation = T2.Occupation AND STRCMP(T1.Name, T2.Name) >= 0 GROUP BY T1.Name, T1.Occupation ORDER BY Rank, T1.Name) AS MyOccupations GROUP BY Rank;

3.Oracle

代码如下（示例）：

WITH D AS (SELECT NAME, ROWNUM R FROM (SELECT NAME FROM OCCUPATIONS WHERE OCCUPATION='Doctor' ORDER BY 1)),
     P AS (SELECT NAME, ROWNUM R FROM (SELECT NAME FROM OCCUPATIONS WHERE OCCUPATION='Professor' ORDER BY 1)),
     S AS (SELECT NAME, ROWNUM R FROM (SELECT NAME FROM OCCUPATIONS WHERE OCCUPATION='Singer' ORDER BY 1)),
     A AS (SELECT NAME, ROWNUM R FROM (SELECT NAME FROM OCCUPATIONS WHERE OCCUPATION='Actor' ORDER BY 1))
SELECT D.NAME,P.NAME,S.NAME,A.NAME
FROM 
  A FULL OUTER JOIN D ON A.R=D.R  
    FULL OUTER JOIN S ON A.R=S.R
    FULL OUTER JOIN P ON A.R=P.R;

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总结

题目有很多种解法，上面只是其中三种解法，各位博主有其他解法欢迎分享！！！