Question

While the following work fine in SQL Server Management Studio, it just won’t work in C#:

DECLARE @PeriodID AS bigint;
SELECT TOP 1 @PeriodID = PeriodID FROM Periods ORDER BY PeriodID DESC;
IF NOT EXISTS(SELECT * FROM information_schema.columns WHERE COLUMN_NAME = N'PeriodID' AND TABLE_NAME = N'MobilePlans')
BEGIN
    BEGIN
    ALTER TABLE MobilePlans ADD PeriodId bigint NULL
    END
    BEGIN
    UPDATE MobilePlans SET PeriodID = @PeriodID
    END
    BEGIN
    ALTER TABLE MobilePlans ALTER COLUMN PeriodID bigint NOT NULL
    END
END

In C#, it keeps telling me Invalid column name 'PeriodID'. and after spending a couple of hours searching, I thought I’d ask here.

While searching, I came across http://bytes.com/topic/c-sharp/answers/258520-problem-sqlcommand-t-sql-transaction, but I couldn’t really translate my conditional query to that.

Why can’t C# do the same as the Management studio?

Is there another way to do what the query does, that works in C#? I need to perform this on 400 databases, so I’d really like a script to do it for me.

Thanks in advance!

SQL server version is 2008.
Manager version is 2008 (10.0.2531).
.NET framework version is 2.0.

Answer 1

I get “invalid column name ‘PeriodID'” running it in Management Studio, if the table doesn’t already have the PeriodID column.

Repro:

create table Periods (
    PeriodID bigint not null
)
go
insert into Periods(PeriodID) select 1
go
create table MobilePLans (
    BLah int not null
)
go
insert into MobilePLans(BLah) select 2
go
DECLARE @PeriodID AS bigint;
SELECT TOP 1 @PeriodID = PeriodID FROM Periods ORDER BY PeriodID DESC;
IF NOT EXISTS(SELECT * FROM information_schema.columns WHERE COLUMN_NAME = N'PeriodID' AND TABLE_NAME = N'MobilePlans')
BEGIN
    BEGIN
    ALTER TABLE MobilePlans ADD PeriodId bigint NULL
    END
    BEGIN
    UPDATE MobilePlans SET PeriodID = @PeriodID
    END
    BEGIN
    ALTER TABLE MobilePlans ALTER COLUMN PeriodID bigint NOT NULL
    END
END

The reason is simple – SQL Server tries to compile each batch completely. If the column already exists, then the UPDATE statement can be compiled. If not, you get the error.

If you put the update inside an Exec:

EXEC('UPDATE MobilePlans SET PeriodID = ' + @PeriodID)

Then it will be compiled at the point that the column does exist.