How to check if a Constraint exists in Sql server?

Question

I have this sql:

ALTER TABLE dbo.ChannelPlayerSkins
    DROP CONSTRAINT FK_ChannelPlayerSkins_Channels

but apparently, on some other databa

Answer 1

I use this to check for and remote constraints on a column. It should have everything you need.

DECLARE
  @ps_TableName VARCHAR(300)
  , @ps_ColumnName VARCHAR(300)

SET @ps_TableName = 'mytable'
SET @ps_ColumnName = 'mycolumn'

DECLARE c_ConsList CURSOR LOCAL STATIC FORWARD_ONLY FOR
    SELECT
    'ALTER TABLE ' + RTRIM(tb.name) + ' drop constraint ' + sco.name AS csql
    FROM
        sys.Objects tb
        INNER JOIN sys.Columns tc on (tb.Object_id = tc.object_id)
        INNER JOIN sys.sysconstraints sc ON (tc.Object_ID = sc.id and tc.column_id = sc.colid)
        INNER JOIN sys.objects sco ON (sc.Constid = sco.object_id)
    where
        tb.name=@ps_TableName
        AND tc.name=@ps_ColumnName
OPEN c_ConsList
FETCH c_ConsList INTO @ls_SQL
WHILE (@@FETCH_STATUS = 0) BEGIN

    IF RTRIM(ISNULL(@ls_SQL, '')) <> '' BEGIN
        EXECUTE(@ls_SQL)
    END
    FETCH c_ConsList INTO @ls_SQL
END
CLOSE c_ConsList
DEALLOCATE c_ConsList