TSQL Pivot 长列列表-数据库问题

TSQL Pivot Long List of Columns(TSQL Pivot 长列列表)

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问题描述

我希望使用数据透视函数将列的行值转换为单独的列.该列中有 100 多个不同的值，并且对数据透视函数的for"子句中的每个值进行硬编码将非常耗时，并且从可维护性的目的来看也不好.我想知道是否有更简单的方法来解决这个问题?

I am looking to use pivot function to convert row values of a column into separate columns. There are 100+ distinct values in that column and hard-coding each and every single value in the 'for' clause of the pivot function would be very time consuming and not good from maintainability purposes. I was wondering if there is any easier way to tackle this problem?

谢谢

推荐答案

您可以在 PIVOT 中使用动态 SQL 进行此类查询.动态 SQL 将获取您要在执行时转换的项目列表，从而无需对每个项目进行硬编码:

You can use Dynamic SQL in a PIVOT for this type of query. Dynamic SQL will get the list of the items that you want to transform on execution which prevents the need to hard-code each item:

DECLARE @cols AS NVARCHAR(MAX),
    @query  AS NVARCHAR(MAX)

SET @cols = STUFF((SELECT distinct ',' + QUOTENAME(c.condition_id) 
            FROM t c
            FOR XML PATH(''), TYPE
            ).value('.', 'NVARCHAR(MAX)') 
        ,1,1,'')


set @query = 'SELECT memid, ' + @cols + ' from 
            (
                select MemId, Condition_id, condition_result
                from t
           ) x
            pivot 
            (
                sum(condition_result)
                for condition_id in (' + @cols + ')
            ) p '


execute(@query)

参见 SQL Fiddle with Demo

如果您发布需要转换的数据样本，那么我可以调整我的查询来演示.

If you post a sample of data that you need to transform, then I can adjust my query to demonstrate.

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