Concatenate multiple rows

问题

I'm using Microsoft SQL Server 2005.

I think I need a sub-query.

I'm looking for one (1) row per customer, with the AvailableAction field be a concatenation of all the Actions for each customer.

use tempdb
GO
IF DB_ID('myDatabase') IS NOT NULL
  DROP DATABASE myDatabase
go
CREATE DATABASE myDatabase 
GO
USE myDatabase
GO
create table Cust(
CustID Int Identity Primary Key,
CustName Varchar(255)
)
GO
INSERT INTO Cust(CustName) values('One')
INSERT INTO Cust(CustName) values('Two')
GO
CREATE TABLE Action(
ActionID Int Identity(101,1) Primary Key,
ActionName Varchar(128)
)
GO
INSERT INTO Action(ActionName) VALUES('Insert')
INSERT INTO Action(ActionName) VALUES('Update')
INSERT INTO Action(ActionName) VALUES('Delete')
INSERT INTO Action(ActionName) VALUES('Print')
GO
create table CustAction(
CustActionID Int Identity Primary Key,
CustID Int,
ActionID Int
)
GO
INSERT INTO CustAction(CustID,ActionID) VALUES(1,101)
INSERT INTO CustAction(CustID,ActionID) VALUES(1,102)
INSERT INTO CustAction(CustID,ActionID) VALUES(2,102)
INSERT INTO CustAction(CustID,ActionID) VALUES(2,103)
GO
SELECT Cust.CustID,CustName,ActionName
FROM CustAction
JOIN Cust
ON CustAction.CustID = Cust.CustID
JOIN Action
ON CustAction.ActionID = Action.ActionID
GO
SELECT 
Cust.CustID,CustName,
'<option value="' + CAST(Action.ActionID AS Varchar) + '">' + ActionName + '</option>' AS AvailableAction
FROM CustAction
JOIN Cust
ON CustAction.CustID = Cust.CustID
JOIN Action
ON CustAction.ActionID = Action.ActionID

I would like the output to be:

CustID AvailableAction

    1  <option value="101">Insert</option><option value="102">Update</option>
    2  <option value="102">Update</option><option value="103">Delete</option>

回答1:

For 2005+

SELECT CustID
     , (SELECT ca.ActionID [@value]
             , ActionName [text()]
          FROM dbo.CustAction ca
         INNER JOIN dbo.Action ON ca.ActionID = Action.ActionID
         WHERE ca.CustID = c.CustID
           FOR XML PATH('option'), TYPE) AvailableAction
  FROM dbo.Cust c

I don't think you'll be able to get this with FOR XML EXPLICIT, so if this is 2000 you're out of luck (as far as simple solutions go).

回答2:

Here's a way that I'm sure will be bettered by someone that knows SQL Server XML!

 SELECT CustID  ,
       CustName,
       REPLACE(REPLACE(
       ( SELECT '<option value="' + CAST(ACTION.ActionID AS VARCHAR) + '">' + ActionName + '</option>'
       FROM    ACTION
               JOIN CustAction
               ON      CustAction.CustID = Cust.CustID
       WHERE   CustAction.ActionID       = ACTION.ActionID FOR XML PATH('')
       )
       ,'&lt;','<'),'&gt;','>') AvailableAction
FROM   Cust

来源：https://stackoverflow.com/questions/3197626/concatenate-multiple-rows