Primary Key Constraints A table typically has a column or combination of columns that contain values that uniquely identify each row in the table. This column, or columns, is called the primary key ...

2. There can be UNIQUE columns, but only one primary key in a table 3. A primary key is a field in a table, which uniquely identifies each row/record in a database table ERROR: Key (item_id)=(1) ...

In mysql, the primary key constraint is used to uniquely identify each record in a table.primary key contains unique values only and the column defined as primary key column can not be null. a table ...

When I am working with an Oracle database, I still find myself using SQL*Plus for many quick and dirty database queries. In particular, I often look up constraints in SQL*Plus. In this post, I ...

A referential integrity constraint is created when a primary key integrity constraint in one data file is referenced by a foreign key integrity constraint in another data file.