Question

我从带有不明确的列名的表中提取数据（表1）。还有另一个表格，其中包含模糊列名称含义的字典（表2）。数据集中有足够的列，我不想输入'SELECT a AS a_name，b AS b_name ...'。我想从表1中获取所有数据，但是根据表2重命名列。

示例表1：

id  A1   A2   A3  B1 B2 B3
1  foo1 foo2 foo3 1  1  0
2  bar1 bar2 bar3 2  3  4
...

示例表2：

column_ref   col_definition
        A1           apples
        A2        aardvarks
        A3         androids
        B1            bears
        B2            beers
        B3            boats

示例输出：

id apples aardvarks   androids  bears beers boats
1    foo1      foo2       foo3      1     1     0
2    bar1      bar2       bar3      2     3     4
...

这个问题很接近： Retrieve column names from a different table?

除了我必须每列输入/复制约200次。

我有没有办法加入他们的名字？或类似的东西？

Answer 1

这几乎可以做你想要的，除非它不保留数据类型。我使用了nvarchar。

/* Create new table for data with new column headers */
create table Table_3
(
/* Temp column, will delete later */
T3 varchar
)

/* Select column definitions into temp table */
select * 
into #TempTable
from
(
    select a.col_definition from Table_2 a
    join 
    (
        /* Get column names for Table_1 to join on */
        select column_name from SANDBOX.INFORMATION_SCHEMA.COLUMNS
        Where TABLE_NAME = N'Table_1'
    ) b
    on a.column_ref=b.column_name
) T

declare @ColDf nvarchar(max)
declare @sql nvarchar(max)

/* Loop through column definitions in #TempTable */
while exists (select * from #TempTable)
begin

        select @ColDf = (select top 1 ColDf
                        from #TempTable
                        order by ColDf asc)

        /* Add column using each column definition as column name */
        set @sql = 'alter table Table_3 add ' + @ColDf + ' nvarchar(max)'
        exec (@sql)

        delete #TempTable
        where ColDf = @ColDf

end

/* Remove temp table */ 
drop table #TempTable

/* Remove temp column */
alter table Table_3
drop column T3

/* Copy data from Table_1 into Table_3 */
insert into Table_3
select * from Table_1

/* View results */
select * from Table_3

从不同的表中使用列名称提取数据

1 个答案: