如果 SQL 有字典和 for-each，则在 table 中插入新值

Question

假设我的 table of myTable 有一个 column1，其中已经有一些值。现在我得到了一些新值，我应该将它们放入名为 'column2' 的新创建的列中。它们是一对一关联在一起的，并且是唯一的。例如：

column1 | column2
-----------------
'ABCHi' | 'newOH'
-----------------
'TER12' | 'Meow2'
-----------------
'WhatE' | 'BMW26'
-----------------

所以我可以这样说：

Update myTable SET column2 = 'newOH' WHERE column1 = 'ABCHi'

并对每一行都这样做（我有 32 行要做）。但我想也许有一种“更好”的方式来做到这一点？就像是 C# 我可以说填充一个 dictionary 然后做一个 for-each 循环！

Answer 1

您可以使用 With 子句将“词典”创建为内联视图。

这里是fiddlehttps://dbfiddle.uk/?rdbms=sqlserver_2017&fiddle=c0e1393785082fd5cd9352d513b76af6

with Dictionary as(
  select 'ABCHi' as column1, 'newOH' as column2 
  union all
  select 'TER12' as column1, 'Meow2' as column2 
  union all
  select 'WhatE' as column1, 'BMW26' as column2
  )
UPDATE t
SET  t.column2=dictionary.column2
FROM mytable t JOIN Dictionary ON t.column1 = Dictionary.column1

Answer 2

您可以使用 Table Value Constructor:

declare @Samples as Table ( Column1 VarChar(10), Column2 VarChar(10) );

-- Initialize the sample data.
insert into @Samples ( Column1 ) values
  ( 'ABCHi' ), ( 'TER12' ), ( 'WhatE' )
select * from @Samples;

-- Update the second column.
update OSamples
  set Column2 = NSamples.Column2
  from @Samples as OSamples inner join
    ( values
      ( ( 'ABCHi' ), ( 'newOH' ) ),
      ( ( 'TER12' ), ( 'Meow2' ) ),
      ( ( 'WhatE' ), ( 'BMW26' ) )
      ) as NSamples( Column1, Column2 )
    on OSamples.Column1 = NSamples.Column1;
select * from @Samples;

DBfiddle.

如果 SQL 有字典和 for-each，则在 table 中插入新值

Inserting new values in a table if SQL had Dictionary and for-each

sql

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