How to change the column length of a primary key in SQL Server?

See below sample example how to increase size of the primary column

1. Create a sample table

   create table abc (id varchar(10) primary key)

2. Find primary constraint in key constraints tables

   select object_name(object_id),* from sys.key_constraints where object_name(parent_object_id) = 'abc

3. Drop constraint

   ALTER TABLE abc DROP CONSTRAINT PK__abc__3213E83F74EAC69B

   (Replace PK__abc__3213E83F74EAC69B with constraint name you receive.)

4. Add not null

   ALTER TABLE abc alter column id varchar(20) NOT NULL;

5. Add primary key again

   ALTER TABLE abc ADD CONSTRAINT MyPrimaryKey PRIMARY KEY (id)

ALTER TABLE <Table_Name>
DROP CONSTRAINT <constraint_name>

ALTER TABLE table_name
ALTER COLUMN column_name datatype

ALTER TABLE <Table_Name>
ADD CONSTRAINT <constraint_name> PRIMARY KEY (<Column1>,<Column2>)