使用 CASE WHEN 按两列排序-数据库问题

Order by two columns with usage of CASE WHEN(使用 CASE WHEN 按两列排序)

本文介绍了使用 CASE WHEN 按两列排序的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！

问题描述

我有一个这样的查询:

SELECT 
    ROW_NUMBER() OVER(ORDER BY USER_FNM, USER_LNM) AS ROW_NUM,
    USER_TEL, USER_FAX, USER_MOB            
FROM 
    BAUSER      
ORDER BY            
    CASE 
       WHEN @cOrderBy = 'USER_FNM_USER_LNM ASC' THEN USER_LNM 
    END ASC,
    CASE 
       WHEN @cOrderBy = 'USER_FNM_USER_LNM DESC' THEN USER_LNM 
    END DESC,
    CASE 
       WHEN @cOrderBy IS NULL THEN USER_KEY 
    END ASC
    OFFSET @iStartIndex ROWS
    FETCH NEXT @iRowsPerPage ROWS ONLY

我想做的是按两列排序 - 但这显示语法错误:

What I would like to do is sorting by two columns - but this is showing syntax error:

CASE WHEN @cOrderBy = 'USER_FNM_USER_LNM ASC' THEN USER_LNM, USER_FNM END ASC

知道在这种情况下如何按两列排序吗?

Any idea how to sort by two columns in this case?

推荐答案

CASE 是一个返回单个表达式/值的表达式.您需要为每一列编写一个 CASE 语句:

CASE is an expression that returns a single expression/value. You need to write one CASE statement per column:

ORDER BY            
CASE WHEN @cOrderBy = 'USER_FNM_USER_LNM ASC'        THEN USER_LNM END ASC,
CASE WHEN @cOrderBy = 'USER_FNM_USER_LNM DESC'       THEN USER_LNM END DESC,
CASE WHEN @cOrderBy IS NULL                          THEN USER_KEY END ASC,

CASE WHEN @cOrderBy = 'USER_FNM_USER_LNM ASC'        THEN USER_FNM END ASC,
CASE WHEN @cOrderBy = 'USER_FNM_USER_LNM DESC'       THEN USER_FNM END DESC

更新(反映更新的问题)

由于您有 ROW_NUM 列，您可以按此排序:

Since you have ROW_NUM column, you can sort by that:

CASE WHEN @cOrderBy = 'USER_FNM_USER_LNM ASC'        THEN ROW_NUM END ASC,
CASE WHEN @cOrderBy = 'USER_FNM_USER_LNM DESC'       THEN ROW_NUM END DESC,
CASE WHEN @cOrderBy IS NULL

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