Question

I have a stored procedure which has more than 2000 lines of code .I need to change the table names in from clause based on a condition .The column names will remain same in both the tables .

For example:-

   Declare @condition char(1)
   set @condition=(Select close_flg from log 
                   where  last_run_dt >= 
                  (Select  cur_dt from dt) 
                  )

  --If @condition is 'A' then below sql will execute

   Select a.columnA,
        Case 
         when  @condition='A' then  'D'
         Else 'M'
         END,
         b.ColumnC
   from TableA as a
   inner join TableB as b
   on a.Column=b.Column

Now if @condition is ‘B’ then i need to change the sql as
(Only the inner join is different rest all the columns in the select query are same )

   Select 
   -- the same columns as above 
   from TableC as c
   inner join TableD as d
   on c.Column=d.Column

I want to make my SQL generic to reduce the duplicate code .Is it even possible to do so .

Thanks

Answer 1

You can use dynamic query for your scenario like this :

DECLARE @sqlCommand varchar(1000)
DECLARE @TableName varchar(75)

--If @condition is 'A' then 
Set @TableName = 'your table name'
--else
Set @TableName = 'your other table name'


SET @sqlCommand = 'select * from '+@TableName
EXEC (@sqlCommand)

Now transform above technique according to your scenario.