SQL Column Not Found: Added earlier in program - sql

Question

I'm using SQL Server 2008. I have a stored procedure with code that looks like this:
if not exists (select column_name from INFORMATION_SCHEMA.columns
where table_name = 'sample_table' and column_name = 'sample_column')
BEGIN
ALTER TABLE Sample_Table
ADD Sample_Column NVARCHAR(50)
END
Update dbo.Sample_Table
SET Sample_Column = '1'
When I execute, I get a "Column Not Found" error because the column doesn't originally exist in Sample_Table-it's added in the procedure. What's the correct way to get around this?
My workaround (below) is to wrap the update statement in an EXEC statement, so that it is forced to create the code and execute after the ALTER TABLE step. But is there a better method?
EXEC ('
Update dbo.Sample_Table
SET Sample_Column = ''1'' ')

Answer 1

If you do not really like your workaround, the only other option seems to be separating your DDL logic from the DML one, i.e. one SP will check/create the column (maybe other columns too, as necessary), another SP sets the value(s).
On the other hand, it looks like you are using your UPDATE statement merely as a means of providing a default value for the newly created column. If that is the case, you might consider an entirely different solution: creating a DEFAULT constraint (no need for the UPDATE statement). Here:
if not exists (select column_name from INFORMATION_SCHEMA.columns
where table_name = 'sample_table' and column_name = 'sample_column')
BEGIN
ALTER TABLE Sample_Table
ADD Sample_Column NVARCHAR(50) NOT NULL
CONSTRAINT DF_SampleTable_SampleColumn DEFAULT ('1');
ALTER TABLE Sample_Table
ALTER COLUMN Sample_Column NVARCHAR(50) NULL;
END
The second ALTER TABLE command is there only to drop the NOT NULL restriction, as it seems like you didn't mean your column to have it. But if you are fine with NOT NULL, then just scrap the second ALTER TABLE.