SQL命令通过硬编码值

Question

我有以下查询：

select 'junior' as type, value 
from mytable 
union 
select 'intermediate' as type, value 
from mytable 
union 
select 'senior' as type, value 
from mytable 

它返回以下数据：

type   value 

Intermediate  10  
Junior   5 
Senior   1 

我只是需要，所以它看起来像这样

Junior   5 
Intermediate 10   
Senior   1 

来重新排序

我不知道哪个订单的子句用于实现通过自定义特定值排序，我将如何实现这一目标？

Answer 1

您需要添加的第三列中，例如所谓的排序。然后，适当的整数值分配给它，

select 'junior' as type, value, 1 as sortorder 
from mytable 
union 
select 'intermediate' as type, value, 2 as sortorder 
from mytable 
union 
select 'senior' as type, value, 3 as sortorder 
from mytable 
order by 3 

Answer 2

我不知道你是否理解你，但我会提取一列，例如带有整数值的“序列”。它将提供应用自定义订单的能力。

作为一个例子：

select results.type, results.value, results.sequence 
from ( 
    select 'junior' as type, value, 0 as sequence 
    from mytable 
    union 
    select 'intermediate' as type, value, 1 as sequence 
    from mytable 
    union 
    select 'senior' as type, value, 2 as sequence 
    from mytable 
) as results order by results.sequence 

Answer 3

您可以排序增加排序键列或添加一个基于值的简单的case语句。

-- Sort with Case statement 
with sourceData as 
(
    select 'junior' type, 5 value 
    union all 
    select 'intermediate' type, 10 value 
    union all 
    select 'senior' type, 1 value 
) 
select * 
from sourceData 
order by 
    case type 
    when 'junior' then 0 
    when 'intermediate' then 1 
    when 'senior' then 2 
    else null 
    end 

SQL Fiddle进行测试。

Answer 4

试试这个。

选择类型，值从 （ 选择类型，值，ROW_NUMBER（）以上（按类型顺序）rowno 从#mytable 联合 选择类型，值，ROW_NUMBER（）以上（按类型顺序） rowno 从#mytable 工会 选择类型，值，ROW_NUMBER（）以上（按类型顺序）rowno 从#mytable ）的订单，由2递减