Trying to create a large dynamic query, keeps getting truncated

Question

I have a SQL query in SQL server where I am trying to create large query with 'union' on a large number of databases. However, the query keeps getting truncated. According to my research this shouldn't happen if all the varchar are cast to varchar(MAX). I tried doing this, however, it still gets truncated. The final query should be in the @finalQuery varible. Can anyone help with the query below?

DECLARE @name VARCHAR(MAX) -- database name  
DECLARE @path VARCHAR(MAX) -- path for backup files  
DECLARE @fileName VARCHAR(MAX) -- filename for backup  
DECLARE @fileDate VARCHAR(MAX) -- used for file name 
DECLARE @executeQuery VARCHAR(MAX)
DECLARE @finalQuery VARCHAR(MAX)

SET @finalQuery = ''
DECLARE db_cursor CURSOR FOR
SELECT name
FROM master..sysdatabases
WHERE name NOT IN (CAST('master' AS VARCHAR(MAX)),CAST('model' AS VARCHAR(MAX)),CAST('msdb' AS VARCHAR(MAX)),CAST('tempdb' AS VARCHAR(MAX)))  
OPEN db_cursor
FETCH NEXT FROM db_cursor INTO @name
WHILE @@FETCH_STATUS = 0
BEGIN

SET @executeQuery=CAST(
 'SELECT TOP 1000 
       [EmailAddress] as ''Email Address''
      ,[FirstName] as ''First Name''
      ,[LastName] as ''Last Name''
      ,[LastLogin] as ''Last Login'',
        Name as ''User Role''
  FROM '+@name+'.[dbo].[User] c
  INNER JOIN 
  (  SELECT * FROM '+@name+'.[dbo].[SecurityRole] as a 
     INNER JOIN '+@name+'.[dbo].[SecurityRoleToUser] as b
     ON (a.ID=b.SecurityRoleID)
  ) d     
  ON (c.ID=d.UserID)
  WHERE IsActive=1' AS VARCHAR(MAX))

  --PRINT @executeQuery
  --PRINT @name
  --PRINT @executeQuery
  SET @finalQuery = CAST(@executeQuery+' UNION ALL ' +@finalQuery AS VARCHAR(MAX))
  --PRINT @executeQUery
    --EXEC (@executeQuery)
FETCH NEXT FROM db_cursor INTO @name

END
CLOSE db_cursor
DEALLOCATE db_cursor
PRINT @finalQuery
--EXEC(@finalQuery)

Answer 1

You are better off without doing a UNION across so many databases. And you don't need to. Also, database names, etc are all sysname which equates to NVARCHAR(128) so best to use NVARCHAR(MAX) instead of VARCHAR(MAX).

Step 1: Less complicated query generation

DECLARE @DatabaseName sysname;

DECLARE @Query NVARCHAR(MAX),
        @Template NVARCHAR(MAX);

SET @Query = '';
SET @Template = N'USE [?];
       SELECT TOP 1000 
       [EmailAddress] as [Email Address]
      ,[FirstName] as [First Name]
      ,[LastName] as [Last Name]
      ,[LastLogin] as [Last Login],
        Name as [User Role]
  FROM [dbo].[User] c
  INNER JOIN 
  (  SELECT * FROM [dbo].[SecurityRole] as a 
     INNER JOIN [dbo].[SecurityRoleToUser] as b
     ON (a.ID=b.SecurityRoleID)
  ) d     
  ON (c.ID=d.UserID)
  WHERE IsActive = 1;

';

SELECT @Query = (@Query + REPLACE(@Template, N'?', sd.[name]))
FROM   sys.databases sd
WHERE  sd.[name] NOT IN (N'master', N'model', N'msdb', N'tempdb')
AND    HAS_DBACCESS(sd.[name]) = 1;

--EXEC(@Query); -- uncomment when not debugging

SELECT LEN(@Query); -- 9506 on my system -- comment out if debugging
print @query; -- truncates at 4000 chars for NVARCHAR -- comment out if debugging

Step 2: Not needing a UNION

Instead of using a UNION to get everything into a single result set, just insert multiple result sets into a local temporary table.

CREATE TABLE #tmp (DatabaseName sysname NOT NULL,
                   EmailAddress NVARCHAR(200), FirstName NVARCHAR(50),
                   LastName NVARCHAR(50), LastLogin DATETIME, UserRole VARCHAR(50);

DECLARE @Query NVARCHAR(MAX),
        @Template NVARCHAR(MAX);

SET @Query = '';
SET @Template = N'USE [?];
       SELECT TOP 1000
       DB_NAME() AS [DatabaseName],
       [EmailAddress] as [Email Address]
      ,[FirstName] as [First Name]
      ,[LastName] as [Last Name]
      ,[LastLogin] as [Last Login],
        Name as [User Role]
  FROM [dbo].[User] c
  INNER JOIN 
  (  SELECT UserID, Name--* -- see Step #3 below
     FROM [dbo].[SecurityRole] sr
     INNER JOIN [dbo].[SecurityRoleToUser] srtu
             ON sr.ID = srtu.SecurityRoleID
  ) d     
         ON c.ID = d.UserID
  WHERE IsActive = 1;

';

SELECT @Query = (@Query + REPLACE(@Template, N'?', sd.[name]))
FROM   sys.databases sd
WHERE  sd.[name] NOT IN (N'master', N'model', N'msdb', N'tempdb')
AND    HAS_DBACCESS(sd.[name]) = 1;

INSERT INTO #tmp (DatabaseName, EmailAddress, FirstName, LastName, LastLogin, UserRole)
  EXEC(@Query);

SELECT * FROM #tmp;

Step 3:

It is probably best not use SELECT * in your SELECT * FROM [dbo].[SecurityRole] as a subquery. Just select the fields that you need as it will be more likely to use indexes. It looks like you just need two fields: UserID, Name