Question

I need to add a composite primary key (2 columns) to an already existing table. This key will also be a clustered index, so the order of the columns is important.

I am using the following script:

ALTER TABLE [Table] 
  ADD CONSTRAINT [PK_Table] 
  PRIMARY KEY CLUSTERED ([Col1] ASC, [Col2] ASC)

I need Col1 to be the first column of the clustered index, followed by Col2.

My question is if this script will do it (or do I need to explicitly set the order somehow?).

Appreciate it.

Answer 1

That T-SQL statement is doing exactly what you say you need.

The order of the columns is the order in which you write them down in your T-SQL statement – there’s no need nor any way to otherwise specify their order.

Your T-SQL statement will create a clustered index with Col1 first, followed by Col2 – just as you want it to be.