When I use this script:

```
IF OBJECT_ID('dbo.TableX', 'U') IS NOT NULL 
    DROP TABLE dbo.TableX

CREATE TABLE TableX
(
    ...
    ...
    ...

    CONSTRAINT TableX PRIMARY KEY (column1, column2, column3)
)

```

I get an error 

> 
> An object with the name 'TableX' already exist in the database
> 
> 
> 

but that is only when I use the `CONSTRAINT` line.

Why do I get an error only when I use `CONSTRAINT` and how can I solve it?