连接多行 [英] Concatenate multiple rows

问题描述

我使用的是 Microsoft SQL Server 2005.

I'm using Microsoft SQL Server 2005.

我想我需要一个子查询.

I think I need a sub-query.

我正在为每个客户寻找一 (1) 行，AvailableAction 字段是每个客户的所有操作的串联.

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

我希望输出为:

CustID AvailableAction

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

推荐答案

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

我认为您无法使用 FOR XML EXPLICIT 获得此值，因此如果这是 2000，那么您就不走运了(就简单的解决方案而言).

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).

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