MySQL table-level constraints and column-level constraints

A constraint established on a data column, called a column-level constraint

Constraints that are established on multiple data columns, called Table-level constraints

A column-level constraint can be life when a column is defined, or it can be declared after a column definition.

Table-level constraints can only be declared after a column definition.

Not null and default only exist for column-level constraints.

PRIMARY key, UNIQUE, FOREIGN key both table-level and column-level constraints exist.

MySQL table-level constraints and column-level constraints