《Mysql應用數(shù)據(jù)庫實現(xiàn)行列轉換(mysql示例)》要點:
本文介紹了Mysql應用數(shù)據(jù)庫實現(xiàn)行列轉換(mysql示例),希望對您有用。如果有疑問,可以聯(lián)系我們。
MYSQL教程這篇文章通過sql示例代碼給大家介紹了mysql數(shù)據(jù)庫如何實現(xiàn)行列轉換,下面話不多說,直接來看示例代碼吧.
MYSQL教程原表:
MYSQL教程
表名 :user
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name | course | grade
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zhangsan | Java | 70
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zhangsan | C++ | 80
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lisi | java | 90
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lisi | C# | 60
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MYSQL教程用一條 SQL 語句得到如下形式:
MYSQL教程
----------------------------------------
name | java | C++ | C#
----------------------------------------
zhangsan | 70 | 80 | null
----------------------------------------
lisi | 90 | null | 60
----------------------------------------
MYSQL教程方案一
MYSQL教程
select name,
sum(case when course='java' then grade end) as java,
sum(case when course='C++' then grade end) as C++,
sum(case when course='C#' then grade end) as C#
from test group by name
MYSQL教程方案二
MYSQL教程
select distinct c.`name` AS name,
(select grade from test where name = c.`name` and course = 'java' )as java,
(select grade from test where name = c.`name` and course = 'C++' )as C++,
(select grade from test where name = c.`name` and course = 'C#' )as C#
from test c
MYSQL教程總結
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