You can modify a primary key in sql server 2017 by using sql server management studio or transact-sql. you can modify the primary key of a table by changing the column order, index name, clustered option, or fill factor.. A primary key is a special case of an index -- specifically, a primary key is a unique identifier for an individual row in a table. in most cases, this is implemented using an indexing structure, which allows you to access that single row rapidly by using the primary key column(s) in a predicate.. Hello, i have a table with having primary key and have data in it. nearly 10 table are referencing the primary key of that table as foreign key. now i want to update value of primary key column. please help me with the same. thanks & regards