SQL: Creating In-Line Table Function inside Cursor - sql

Question

I am trying to run an SQL script that will create a function on each of my databases and then use that function to populate a temporary table, which is then used as the source for another cursor that is used to rebuild indexes. however, the problem I have is that the function is only be created on the Database to which I am currently connected, even though I'm using 'Use Database' in my cursor. I have copied the script below, which has been written as to isolate the issue (so it isn't efficient yet).
IF OBJECT_ID (N'sp_index_maintenance', N'P') IS NOT NULL
DROP Proc sp_index_maintenance;
GO
Create proc sp_index_maintenance
AS
BEGIN
CREATE TABLE #T1
(
Database_Name NVARCHAR(MAX),
[Object_Name] NVARCHAR(MAX),
Index_Name NVARCHAR(MAX),
Index_ID INT,
Index_Type_Desc NVARCHAR(MAX),
AVG_Fragmentation_in_percent INT,
Fragment_Count INT,
Page_Count INT
)
DECLARE #DB as nvarchar(100);
DECLARE #Command as NVARCHAR(MAX);
DECLARE #FetchFragStatus AS NVARCHAR(max);
DECLARE #Create_Function NVARCHAR(Max);
DECLARE #Drop_Function NVARCHAR(MAX);
DECLARE DB_USE cursor for
SELECT [Name] FROM sys.databases
OPEN DB_USE
FETCH NEXT FROM DB_USE
INTO #DB
WHILE ##FETCH_STATUS = 0
BEGIN
SET #Command = 'USE ' + #DB
SET #Drop_Function = 'USE ' + #DB + ' IF OBJECT_ID (N''dbo.Index_fragmentation'', N''IF'') IS NOT NULL
DROP Function dbo.index_fragmentation'
SET #Create_Function =
'Create function dbo.index_fragmentation()
RETURNS TABLE AS
RETURN
(
SELECT
DB_NAME(database_ID) AS Database_Name,
OBJECT_NAME(ps.object_id) as [Object_Name],
i.Name AS Index_Name,
ps.index_id,
index_type_desc,
avg_fragmentation_in_percent,
fragment_count,
page_count
FROM
sys.dm_db_index_physical_stats(DB_ID(), NULL, NULL, NULL, ''Limited'') AS ps
INNER JOIN
sys.indexes AS i WITH (NOLOCK)
ON ps.[object_id] = i.[object_id]
AND ps.index_id = i.index_id
WHERE database_id = DB_ID()
--AND page_count > 500
AND avg_fragmentation_in_percent >= 20)'
PRINT (#command)
EXEC sp_executesql #Command
--PRINT (#Drop_Function)
--EXEC (#Drop_Function)
PRINT (#Create_function)
EXEC sp_executesql #Create_function
FETCH NEXT FROM DB_USE
INTO #DB
END
CLOSE DB_USE
DEALLOCATE DB_USE
DECLARE DB_USE cursor for
SELECT [Name] FROM sys.databases
OPEN DB_USE
FETCH NEXT FROM DB_USE
INTO #DB
WHILE ##FETCH_STATUS = 0
BEGIN
SET #FetchFragStatus = 'USE ' + #DB +
' INSERT INTO #T1 (Database_Name, Object_Name, Index_Name, index_Id, index_type_desc, avg_fragmentation_in_percent, fragment_count, page_count)
SELECT * FROM dbo.Index_Fragmentation()'
PRINT (#FetchFragStatus);
EXEC (#FetchFragStatus);
FETCH NEXT FROM DB_USE
INTO #DB
END
CLOSE DB_USE
DEALLOCATE DB_USE
--DECLARE #DB_Name NVARCHAR(100);
--DECLARE #Index_Name NVARCHAR(100);
--DECLARE #Alter_index NVARCHAR(MAX);
--DECLARE #Obj_Name NVARCHAR(MAX);
--
--DECLARE Fragmented_index_Cur Cursor For
--SELECT Database_Name, Index_Name, [Object_Name]
--FROM #T1
--
--OPEN Fragmented_index_cur
--FETCH NEXT FROM Fragmented_index_cur
--INTO
--#DB_Name, #Index_Name, #Obj_Name
--WHILE ##FETCH_STATUS = 0
--BEGIN
--SET #Command = 'USE ' + #DB_NAME
--SET #Alter_index = 'ALTER Index ' + #Index_Name + ' ON ' + #Obj_Name + ' REBUILD;'
--PRINT (#command)
--EXEC (#command)
--PRINT (#Alter_Index)
--EXEC (#Alter_index)
--
--FETCH NEXT FROM Fragmented_index_cur
--INTO #DB_Name, #Index_Name, #Obj_Name
--
--END
--CLOSE Fragmented_index_cur
--DEALLOCATE Fragmented_index_cur
SELECT * FROM #T1
RETURN;
END
EXEC sp_index_maintenance

Answer 1

Best way to execute your script against all database is to use Microsoft's EXEC sys.sp_MSforeachdb undocumented function, that comes in very handy, if you google you can find a lot of examples of its use. By using this function you can get rid of bad cursors that many people in community will chastise you for. I'm all for use of cursors just need to know when to use them.
here is simplified version of your query. This will get bad indexes in all database and store into temp table.
CREATE PROCEDURE myBadIndexFromAllDBs
AS
BEGIN
CREATE TABLE #tempTable
(
Database_Name VARCHAR(250)
,OBJECT_NAME VARCHAR(250)
,Index_Name VARCHAR(250)
,Index_id INT
,index_type_desc VARCHAR(60)
,avg_fragmentation_in_percent FLOAT
,fragment_count BIGINT
,page_count BIGINT
)
EXEC sys.sp_MSforeachdb
'
use [?]
INSERT INTO #tempTable
SELECT DB_NAME(database_ID) AS Database_Name
,OBJECT_NAME(ps.object_id) AS [Object_Name]
,i.Name AS Index_Name
,ps.index_id
,index_type_desc
,avg_fragmentation_in_percent
,fragment_count
,page_count
FROM sys.dm_db_index_physical_stats(DB_ID(), NULL, NULL, NULL, ''Limited'') AS ps
INNER JOIN sys.indexes AS i WITH ( NOLOCK )
ON ps.[object_id] = i.[object_id]
AND ps.index_id = i.index_id
WHERE database_id = DB_ID()
AND avg_fragmentation_in_percent >= 50
'
SELECT *
FROM #tempTable
END

Answer 2

each sp_executesql is run under it's own instance, so the sp_executesql #Command only puts its call as using the other database.
Try moving the 'USE ' + #DB into the #Create_Function