Introduction to Programming

CREATE, ALTER, and DROP table

The standard SQL statement for the table creation looks like this:

CREATE TABLE tablename (
  column1 type1,
  column2 type2,
  column3 type3,
  ....
);

The limitations for a table name, column names, and types of values that can be used depend on the particular database.  Here is an example of a command that creates table person in PostgreSQL:

CREATE TABLE person (
  id SERIAL PRIMARY KEY,
  first_name VARCHAR NOT NULL,  last_name VARCHAR NOT NULL,  dob DATE NOT NULL
);

As you can see, we have made the dob (date of birth) column not nullable. That imposes a constraint on our Person Java class that is going to represent the records of this table: its dob field cannot be null. And that was what we have done, you may recall, ...