从 query_to_xml() 输出中提取 XML 值

Question

我正在从 SQL Server 迁移到 PostgreSQL，并且在转换查询时遇到困难

我的 SQL Server 查询：

SELECT * FROM dbo.Stl_Mtr_userdetails AS table1 JOIN( SELECT urmo.urm_userid, 
STUFF((SELECT ',' + urm.urm_role_name FROM dbo.STL_CS_Mtr_userrolemapping urm  
WHERE urm.urm_userid = 'test2' AND urm.urm_status = 'A' AND urm.urm_appid = 'BCA'   
FOR XML PATH('')),1,1,'') [user_roles],urmo.urm_appid FROM dbo.Stl_CS_Mtr_userrolemapping  
urmo WHERE urmo.urm_appid = 'BCA' AND urmo.urm_userid = 'test2'  
GROUP BY urmo.urm_userid,urmo.urm_appid) AS table2 ON  
table1.ud_userid = table2.urm_userid WHERE (table1.ud_userid = 'test2')

PostgreSQL 查询

SELECT * FROM STL_Mtr_userdetails AS table1 JOIN( SELECT urmo.urm_userid,  
query_to_xml('SELECT '','' || urm.urm_role_name FROM STL_CS_Mtr_userrolemapping urm WHERE  
urm.urm_userid = ''test2'' AND urm.urm_status = ''A'' AND   
urm.urm_appid = ''BCA''', true, false, '')  
user_roles,urmo.urm_appid FROM STL_CS_Mtr_userrolemapping urmo   
WHERE urmo.urm_appid = 'BCA' AND urmo.urm_userid = 'test2'   
GROUP BY urmo.urm_userid,urmo.urm_appid) AS table2 ON   
table1.ud_userid = table2.urm_userid WHERE (table1.ud_userid = 'test2')

上述转换后的 PostgreSQL 查询在执行时工作正常并产生以下结果

user_roles 字段。

<table xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">

<row>
  <_x003F_column_x003F_>,role1</_x003F_column_x003F_>
</row>

<row>
  <_x003F_column_x003F_>,role2</_x003F_column_x003F_>
</row>

</table>

我在从 xml 中提取值并将 user_roles 的输出作为 role1,role2 时遇到了困难。

请帮帮我。

Answer 1

如果您需要逗号分隔的角色列表，请使用 string_agg() 而不是 query_to_xml()

SELECT * 
FROM STL_Mtr_userdetails AS table1 
JOIN( 
  SELECT urmo.urm_userid,  
         string_agg(urmo.urm_rol_name, ',') as user_roles,
         urmo.urm_appid 
   FROM STL_CS_Mtr_userrolemapping urmo   
   WHERE urmo.urm_appid = 'BCA'
     AND urm.urm_status = 'A' 
     AND urmo.urm_userid = 'test2'   
   GROUP BY urmo.urm_userid, urmo.urm_appid
) AS table2 ON table1.ud_userid = table2.urm_userid 
WHERE table1.ud_userid = 'test2'