A row value that is updated or deleted by SQL server-either cannot make the row a unique row, or it changes multiple rows

Problems that occur when you update a table that does not have a primary key set:

Cause of the problem:

Most of this is due to the absence of a primary key (PK) that causes several identical data to exist in the same table

When the DBMS is stored, only one piece of data is stored, because the DBMS is optimized to reduce data redundancy. So deleting or updating a duplicate data is reaching

Workaround:

It is recommended to set the primary key to check for the existence of the same row data

A row value that is updated or deleted by SQL server-either cannot make the row a unique row, or it changes multiple rows