In dynamic SQL, table is not being created - sql

Question

I have to use the configurations table to create a table if the table_status is new, and I have written the code but the table 'Dimcampaign' is not being created.

Answer 1

Initially you set #Tablestatus to a SQL statement, but the while loop requires #Tablestatus = 'New'. You should change how you initialize your #Tablestatus variable so that the logic flows into the while loop.
I would guess that you actually want #Tablestatus to be initialized to the value in your dbo.configuration table. For example:
declare #Tablestatus varchar(MAX)
select #Tablestatus = tablestatus from dbo.configuration
That being said, your while loop does not have a way to terminate. For example, inside the loop you should reset #Tablestatus so that it can become something other than 'New' so the loop can end.
For example:
while #Tablestatus = 'New' begin
-- maybe do some stuff here
update dbo.configuration set tablestatus = 'Old'
-- maybe do some other stuff here
select #Tablestatus = tablestatus from dbo.configuration
end
Looking a little more at your post, I don't really understand why you have a while loop there. It looks like you want something like this:
-- Initialize variables with values from dbo.configuration
declare #Tablestatus varchar(MAX)
select #Tablestatus = tablestatus from dbo.configuration
declare #If_New_Table_then_PrimaryKey NVARCHAR(MAX)
select #If_New_Table_then_PrimaryKey = If_New_Table_then_PrimaryKey from dbo.configuration
declare #NewColumn varchar(max)
select #NewColumn = Newcolumn from dbo.configuration
declare #Datatypes NVARCHAR(MAX)
select #Datatypes = Datatypes from dbo.configuration
declare #sql varchar(100)
-- Now that your variables are initialized you
-- can use the variables to take the appropriate action
if #Tablestatus = 'New' and #If_New_Table_then_PrimaryKey = 'Yes'
begin
set #sql = 'Create table' + #tablename + '(' + #Newcolumn + #Datatypes + ' PRIMARY KEY' + '(' + #Newcolumn + ')' + ');'
print (#sql)
exec(#sql)
end
if #Tablestatus = 'Old'
begin
set #sql = 'Alter table' + #tablename + 'ADD' + #Newcolumn + #Datatypes
print (#sql)
exec(#sql)
end

Answer 2

I like playing around with cursors and dynamic SQL. Something like this should do the trick, I'd add a whole lot of checking though! What if tablename contains spaces (you might like to use QUOTENAME), or what if datatypes doesn't contain a valid datatype? Etc etc, I can think of 100 things that can go wrong. Generally, when you want to do this, you need to rethink your design. But I have been in situations where I had to do something similar.
DECLARE #Tablestatus NVARCHAR(4000)
, #tablename NVARCHAR(4000)
, #If_New_Table_then_PrimaryKey NVARCHAR(4000)
, #NewColumn NVARCHAR(4000)
, #Datatypes NVARCHAR(4000)
, #sql NVARCHAR(4000);
DECLARE cur CURSOR LOCAL FAST_FORWARD FOR
SELECT tablestatus
, tablename
, If_New_Table_then_PrimaryKey
, Newcolumn
, Datatypes
FROM dbo.configuration;
OPEN cur;
FETCH NEXT FROM cur
INTO #Tablestatus
, #tablename
, #If_New_Table_then_PrimaryKey
, #NewColumn
, #Datatypes;
WHILE ##FETCH_STATUS = 0
BEGIN;
IF #Tablestatus = 'New'
AND #If_New_Table_then_PrimaryKey = 'Yes'
BEGIN;
SET #sql = N'Create table ' + #tablename + N'(' + #NewColumn + N' ' + #Datatypes + N' PRIMARY KEY' + N'(' + #NewColumn + N')' + N');';
PRINT ( #sql );
EXEC sys.sp_executesql #sql;
END
IF #Tablestatus = 'Old'
BEGIN;
SET #sql = N'Alter table ' + #tablename + N'ADD ' + #NewColumn + N' ' +#Datatypes;
PRINT ( #sql );
EXEC sys.sp_executesql #sql;
END;
FETCH NEXT FROM cur
INTO #Tablestatus
, #tablename
, #If_New_Table_then_PrimaryKey
, #NewColumn
, #Datatypes
END;
CLOSE cur;
DEALLOCATE cur;