DAD 220: Module 3: 3.1: Primary
Key with complete verified
solutions
Primary Key - answer a column or group of columns that identifies
a unique row in a table
Usually the table's first column and appears on the left of the table,
but position isn't significant
represented by a solid circle
Primary Key Rules - answer Values must be unique within the
column
Values may not be NULL
Single Primary Key - answer consists of a single column
Composite Primary Key - answer The primary key formed by
combining two or more columns in a table.
Composite Primary Key Rules - answer Column values, when
grouped together, must be unique.
Ex: The combination (2538, 1) is unique within (ID, Number).
Columns may not contain NULL.
Composite primary keys must be minimal.
Key with complete verified
solutions
Primary Key - answer a column or group of columns that identifies
a unique row in a table
Usually the table's first column and appears on the left of the table,
but position isn't significant
represented by a solid circle
Primary Key Rules - answer Values must be unique within the
column
Values may not be NULL
Single Primary Key - answer consists of a single column
Composite Primary Key - answer The primary key formed by
combining two or more columns in a table.
Composite Primary Key Rules - answer Column values, when
grouped together, must be unique.
Ex: The combination (2538, 1) is unique within (ID, Number).
Columns may not contain NULL.
Composite primary keys must be minimal.
