Sql-server – Run multiple stored procedures in sequence

sql serversql-server-2008-r2stored-procedures

I have a stored procedure written in T-SQL (SQL Server 2008 R2). It is a master procedure that essentially call multiple other subprocedures in sequence. The call and error handling is identical for each one except for the name of the procedure.

In an OO language I would use an abstraction such as an interface or functor and loop over a bunch of objects. That does not work in SQL, but I want to find some way to make this code more concise with less copy and paste repetition. Yes, I know that fundamentally SQL is about set operations and does not support what I want to do very well, but if there is a way, it will make the code much more concise. I also need to capture the result of each stored procedure invocation and do something with it which is not relevant to this question.

Here is what I have so far:

CREATE PROCEDURE dbo.testproc
AS BEGIN
  DECLARE @step INT, @result INT
  DECLARE @tbl TABLE([step] INT, [pname] NVARCHAR(40))

  INSERT INTO @tbl ([step], [pname]) VALUES (1, N'proc1')
  INSERT INTO @tbl ([step], [pname]) VALUES (2, N'proc2')
  INSERT INTO @tbl ([step], [pname]) VALUES (3, N'proc3')
  -- Potentially many more procedures here

  SET @step = 1
  WHILE @step <= (SELECT MAX([step]) FROM @tbl)
  BEGIN
    DECLARE @sql NVARCHAR(60)
    SET @sql = N'EXEC @result = dbo.' + (SELECT [pname] FROM @tbl WHERE [step] = @step)
    EXEC (@sql)
    IF @result <> 0
    BEGIN
      INSERT INTO SomeTable error code and step number
      RETURN
    END
   SET @step = @step + 1
  END
END
GO

When I run the procedure, SQL Server gives me an error because the @result variable that is part of the dynamic SQL is not defined as part of the batch that is contained in the @sql variable. If I modify it like this:

    SET @sql = N'EXEC dbo.' + (SELECT [pname] FROM @tbl WHERE [step] = @step)
    EXEC @result = (@sql)

I get a syntax error.

This works fine except for retrieving the return value of the subprocedures. Is there a way to accomplish my stated goal, and if so, how?

NOTE: based on what I asked here, a cursor would sound like a better implementation than a WHILE loop especially given the table variable. Part of the code that is not essential to this question involves knowing the iteration number, hence the use of a loop control variable.

Best Answer

If you don't need the result values later you can do it shorter this way:

-- procedures to test with
create proc proc1 as print '1' return 0
GO
create proc proc2 as print '2' return 1
GO
create proc proc3 as print '3' return 0
GO

if object_id('dbo.testproc') is null exec('create procedure dbo.testproc as return(0)')
GO
alter PROCEDURE dbo.testproc
AS 
  DECLARE @result INT
        , @sql nvarchar(max) = N''
  DECLARE @tbl TABLE([step] INT, [pname] nvarchar(513))

  INSERT INTO @tbl ([step], [pname]) 
  VALUES (1, N'proc1'), 
         (2, N'proc2'),
         (3, N'proc3')
  -- Potentially many more procedures here

  select @sql = @sql + 'exec @result = ' + QUOTENAME(pname) + ' if @result <> 0 return;'
  from @tbl order by step

  exec sp_executesql @sql, N'@result int output', @result output

  if @result <> 0
    begin
      print 'do your cleanup'
    end 
GO

exec testproc

The variable engine will produce the following query batch

exec @result = [proc1] if @result <> 0 return;
exec @result = [proc2] if @result <> 0 return;
exec @result = [proc3] if @result <> 0 return;

When the batch is executed it will stop executing when there is a @result not zero and keep that value in the output parameter.

More traditional looping

If you want to loop over the procedures. Since there are no parameters (or the parameters are all the same) you can simply call exec @result = @proc 

if object_id('dbo.testproc') is null exec('create procedure dbo.testproc as return(0)')
GO
alter PROCEDURE dbo.testproc
AS 
  DECLARE @result INT
        , @proc sysname
  DECLARE @tbl TABLE([step] INT, [pname] nvarchar(513))

  INSERT INTO @tbl ([step], [pname]) 
  VALUES (1, N'proc1'), 
         (2, N'proc2'),
         (3, N'proc3')
  -- Potentially many more procedures here

  declare c cursor fast_forward local
  for select pname from @tbl order by step

  open c
  fetch next from c into @proc
  while @@FETCH_STATUS = 0
    begin 
      exec @result = @proc 
      if @result <> 0
          BREAK

      fetch next from c into @proc
    end
  close c
  deallocate c

  if @result <> 0
    begin
      print 'do your cleanup'
    end 


GO

exec testproc
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