mysql数据库中列转行

//全部查询出来
SELECT
(case type  when 'MySql数据库' then id else NULL END) as  'MySql数据库',
(case type  when 'SqlServer数据库' then id  else NULL END) as  'SqlServer数据库',
(case type  when 'CSharp' then id else NULL END) as  'CSharp',
(case type  when 'Html' then id else NULL END) as  'Html'
from xiaoyao_blogs_essay;

//查询出他们id的和
SELECT
sum(case type  when 'MySql数据库' then id else NULL END) as  'MySql数据库',
sum(case type  when 'SqlServer数据库' then id  else NULL END) as  'SqlServer数据库',
sum(case type  when 'CSharp' then id else NULL END) as  'CSharp',
sum(case type  when 'Html' then id else NULL END) as  'Html'
from xiaoyao_blogs_essay;

//查询出最大的id
SELECT
max(case type  when 'MySql数据库' then id else NULL END) as  'MySql数据库',
max(case type  when 'SqlServer数据库' then id  else NULL END) as  'SqlServer数据库',
max(case type  when 'CSharp' then id else NULL END) as  'CSharp',
max(case type  when 'Html' then id else NULL END) as  'Html'
from xiaoyao_blogs_essay;

//查询出最小的id
SELECT
min(case type  when 'MySql数据库' then id else NULL END) as  'MySql数据库',
min(case type  when 'SqlServer数据库' then id  else NULL END) as  'SqlServer数据库',
min(case type  when 'CSharp' then id else NULL END) as  'CSharp',
min(case type  when 'Html' then id else NULL END) as  'Html'
from xiaoyao_blogs_essay;

//查询出每列的总数
SELECT
count(case type  when 'MySql数据库' then id else NULL END) as  'MySql数据库',
count(case type  when 'SqlServer数据库' then id  else NULL END) as  'SqlServer数据库',
count(case type  when 'CSharp' then id else NULL END) as  'CSharp',
count(case type  when 'Html' then id else NULL END) as  'Html'
from xiaoyao_blogs_essay;