问题
I need to write a STRING_AGG for my SQL Server 2014 master database. It is a built in function for SQL Server 2017 and Azure SQL.
I have an application that executes stored procedures in an Azure SQL database, some of which use STRING_AGG. In our local development instance, we use a database on our localhost running on an older version of SQL Server. The issue is, because SQL Server 2014 doesn't have access to STRING_AGG, the stored procedures we wrote for our Azure SQL database won't work locally.
The function needs to behave identically to the Azure SQL version so the stored procedures will work in both databases without breaking the local version. I cannot rewrite the stored procedures in the Azure database and I cannot upgrade the version on my localhost.
I've attempted to create a function with the sql_variant type as a parameter, after googling this is as close as I can get to an any type, but I might be incorrect. My function is close I think, but it just returns the result set I pass in. The function needs to work generically, so that it has no knowledge of the table from which the result set is passed in. Luckily, we never use STRING_AGG on a result set of more than one column, so that might make things a little easier. Here's my attempt so far
CREATE FUNCTION dbo.my_STRING_AGG
(@expr sql_variant,
@separator NVARCHAR(MAX))
RETURNS NVARCHAR(MAX)
AS
BEGIN
RETURN
STUFF((SELECT @separator + CONVERT(NVARCHAR(MAX), @expr)
FOR XML PATH('')), 1, 1, '')
END
For a further frame of reference, here is an example of how I use STRING_AGG in my stored procedures
SELECT
STRING_AGG(CAST(TaskCommentAuditId as VARCHAR(255)), ', ')
FROM
TaskCommentAudit;
Suggestions on how to get my function working correctly or another approach?
Thanks!
回答1:
Set the following external function in your database
/*
GROUP_CONCAT string aggregate for SQL Server - https://groupconcat.codeplex.com
Copyright (C) 2011 Orlando Colamatteo
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
See http://www.gnu.org/licenses/ for a copy of the GNU General Public
License.
*/
/*
Installation script for GROUP_CONCAT functions. Tested in SSMS 2008R2.
*/
SET NOCOUNT ON ;
GO
-- !! MODIFY TO SUIT YOUR TEST ENVIRONMENT !!
USE GroupConcatTest
GO
-------------------------------------------------------------------------------------------------------------------------------
=-- Turn advanced options on
EXEC sys.sp_configure @configname = 'show advanced options', @configvalue = 1 ;
GO
RECONFIGURE WITH OVERRIDE ;
GO
=-- Enable CLR
EXEC sys.sp_configure @configname = 'clr enabled', @configvalue = 1 ;
GO
RECONFIGURE WITH OVERRIDE ;
GO
-------------------------------------------------------------------------------------------------------------------------------
SET ANSI_NULLS, ANSI_PADDING, ANSI_WARNINGS, ARITHABORT, QUOTED_IDENTIFIER ON;
SET CONCAT_NULL_YIELDS_NULL, NUMERIC_ROUNDABORT OFF;
GO
IF EXISTS (SELECT * FROM tempdb..sysobjects WHERE id=OBJECT_ID('tempdb..#tmpErrors')) DROP TABLE #tmpErrors
GO
CREATE TABLE #tmpErrors (Error int)
GO
SET XACT_ABORT ON
GO
SET TRANSACTION ISOLATION LEVEL READ COMMITTED
GO
BEGIN TRANSACTION
GO
-------------------------------------------------------------------------------------------------------------------
PRINT N'Creating [GroupConcat]...';
GO
CREATE ASSEMBLY [GroupConcat]
AUTHORIZATION [dbo]
WITH PERMISSION_SET = SAFE;
GO
IF @@ERROR <> 0
AND @@TRANCOUNT > 0
BEGIN
ROLLBACK;
END
IF @@TRANCOUNT = 0
BEGIN
INSERT INTO #tmpErrors (Error)
VALUES (1);
BEGIN TRANSACTION;
END
GO
EXEC sys.sp_addextendedproperty
@name = N'URL',
@value = N'http://groupconcat.codeplex.com',
@level0type = N'ASSEMBLY',
@level0name = N'GroupConcat'
GO
-------------------------------------------------------------------------------------------------------------------
PRINT N'Creating [dbo].[GROUP_CONCAT_D]...';
GO
CREATE AGGREGATE [dbo].[GROUP_CONCAT_D](@VALUE NVARCHAR (4000), @DELIMITER NVARCHAR (4))
RETURNS NVARCHAR (MAX)
EXTERNAL NAME [GroupConcat].[GroupConcat.GROUP_CONCAT_D];
GO
IF @@ERROR <> 0
AND @@TRANCOUNT > 0
BEGIN
ROLLBACK;
END
IF @@TRANCOUNT = 0
BEGIN
INSERT INTO #tmpErrors (Error)
VALUES (1);
BEGIN TRANSACTION;
END
GO
-------------------------------------------------------------------------------------------------------------------
PRINT N'Creating [dbo].[GROUP_CONCAT_S]...';
GO
CREATE AGGREGATE [dbo].[GROUP_CONCAT_S](@VALUE NVARCHAR (4000), @SORT_ORDER TINYINT)
RETURNS NVARCHAR (MAX)
EXTERNAL NAME [GroupConcat].[GroupConcat.GROUP_CONCAT_S];
GO
IF @@ERROR <> 0
AND @@TRANCOUNT > 0
BEGIN
ROLLBACK;
END
IF @@TRANCOUNT = 0
BEGIN
INSERT INTO #tmpErrors (Error)
VALUES (1);
BEGIN TRANSACTION;
END
GO
-------------------------------------------------------------------------------------------------------------------
PRINT N'Creating [dbo].[GROUP_CONCAT_DS]...';
GO
CREATE AGGREGATE [dbo].[GROUP_CONCAT_DS](@VALUE NVARCHAR (4000), @DELIMITER NVARCHAR (4), @SORT_ORDER TINYINT)
RETURNS NVARCHAR (MAX)
EXTERNAL NAME [GroupConcat].[GroupConcat.GROUP_CONCAT_DS];
GO
IF @@ERROR <> 0
AND @@TRANCOUNT > 0
BEGIN
ROLLBACK;
END
IF @@TRANCOUNT = 0
BEGIN
INSERT INTO #tmpErrors (Error)
VALUES (1);
BEGIN TRANSACTION;
END
GO
-------------------------------------------------------------------------------------------------------------------
PRINT N'Creating [dbo].[GROUP_CONCAT]...';
GO
CREATE AGGREGATE [dbo].[GROUP_CONCAT](@VALUE NVARCHAR (4000))
RETURNS NVARCHAR (MAX)
EXTERNAL NAME [GroupConcat].[GroupConcat.GROUP_CONCAT];
GO
IF @@ERROR <> 0
AND @@TRANCOUNT > 0
BEGIN
ROLLBACK;
END
IF @@TRANCOUNT = 0
BEGIN
INSERT INTO #tmpErrors (Error)
VALUES (1);
BEGIN TRANSACTION;
END
GO
-------------------------------------------------------------------------------------------------------------------
IF EXISTS (SELECT * FROM #tmpErrors) ROLLBACK TRANSACTION
GO
IF @@TRANCOUNT>0 BEGIN
PRINT N'The transacted portion of the database update succeeded.'
COMMIT TRANSACTION
END
ELSE PRINT N'The transacted portion of the database update failed.'
GO
DROP TABLE #tmpErrors
-------------------------------------------------------------------------------------------------------------------
GO
source
Then you can use them on the form
**select BlogId, dbo.GROUP_CONCAT(Title) from Posts
group by BlogId**
ruselt
BlogId (No column name)
1 Title 1,Title 2,Title 3,Title 11,Title 12,Title 13,Title 14,Title
2 Title 29,Title 21,Title 10,Title 17,Title 15
3 Title 18,Title 5,Title 8,Title 28
4 Title 7,Title 19
It is necessary to run CLR on the server Thus, when the database is restored to a new server, the CLR must be run
-- Turn advanced options on
EXEC sys.sp_configure @configname = 'show advanced options', @configvalue = 1 ;
GO
RECONFIGURE WITH OVERRIDE ;
GO
-- Enable CLR
EXEC sys.sp_configure @configname = 'clr enabled', @configvalue = 1 ;
GO
RECONFIGURE WITH OVERRIDE ;
GO
来源：https://stackoverflow.com/questions/51331640/how-to-write-the-t-sql-string-agg-function