How to drop a unique constraint from table column?

Question

I have a table 'users' with 'login' column defined as:

[login] VARCHAR(50) UNIQUE NOT NULL

Now I want to remove this unique constraint/index using SQL script. I found its name UQ_users_7D78A4E7 in my local database but I suppose it has a different name on another database.

What is the best way to drop this unique constraint? Or at least any...

Thanks.

Answer 1

SKINDER, your code does not use column name. Correct script is:

declare @table_name nvarchar(256)  
declare @col_name nvarchar(256)  
declare @Command  nvarchar(1000)  

set @table_name = N'users'
set @col_name = N'login'

select @Command = 'ALTER TABLE ' + @table_name + ' drop constraint ' + d.name
    from sys.tables t 
    join sys.indexes d on d.object_id = t.object_id  and d.type=2 and d.is_unique=1
    join sys.index_columns ic on d.index_id=ic.index_id and ic.object_id=t.object_id
    join sys.columns c on ic.column_id = c.column_id  and c.object_id=t.object_id
    where t.name = @table_name and c.name=@col_name

print @Command

--execute (@Command)