Cheat sheet (transfer content from csdn resource tutorial)-Modify Table

Modify Table

The SQL language provides the ALTER TABLE statement to modify the table structure. The basic syntax is as follows:

Alter table table_name

Add [column_name data_type]

[Primary key | constrain]

[Foreign key (column_name)

References ref_table (ref_column)]

Drop [constraint] constraint_name | column column_name

The parameter meanings are as follows:

· Add fields in the Add clause, and set the attribute parameters later.

· Drop clause deletes restrictions or fields. Constraint indicates the deletion restriction; column indicates the deletion of fields.

For example, add a "price" field to the book table in the test database:

Alter table book addprice int