mysql--guarantee the integrity of the data

In order to prevent the production of garbage, it affects the efficiency of database execution.

1 Entity Integrity--the validity of row data unique constraint (unique), PRIMARY KEY constraint (primary key)

2 Domain integrity--The validity of column data is non-null constraint (NOT NULL), DEFAULT constraint (defaults ' format '), checking constraint (check)

3 Referential Integrity--number valid FOREIGN KEY constraint (foreign key)

4 user-defined integrity-Guaranteed custom rules

Auto_increment Self-growth

Constraint foreign Key Name foreign key (column name to set) references table to reference (column of table to reference)-FOREIGN KEY constraint

mysql--guarantee the integrity of the data