SQL Server: drop table primary key, without knowing its name

Question

HI,

Using: SQL Server Database: Northwind

I\'d like to drop a table primary key, without knowing the PK constraint name..

eg, using the Categories table

Answer 1

Adding to Stuart Ainsworth answer, I do not know if PK name has to be unique across different schemas (if so, that answer is ok). Anyway I would choose different sub query for PK name, allowing explicitly to define schema:

declare @PrimaryKeyName sysname = 
    (select CONSTRAINT_NAME 
     from INFORMATION_SCHEMA.TABLE_CONSTRAINTS 
     where CONSTRAINT_TYPE = 'PRIMARY KEY' and TABLE_SCHEMA='dbo' and TABLE_NAME = 'PKTest'
    )

IF @PrimaryKeyName is not null
begin
    declare @SQL_PK NVARCHAR(MAX) = 'alter table dbo.PKTest drop constraint ' + @PrimaryKeyName
    print (@SQL_PK)
    EXEC sp_executesql @SQL_PK;
end