Defining boolean and temporal data columns

Creating PostgreSQL Databases

Darryl Reeves

Industry Assistant Professor, New York University

Boolean and temporal data

CREATE TABLE book (
    isbn CHAR(13) NOT NULL,
    author_first_name VARCHAR(50) NOT NULL,
    author_last_name VARCHAR(50) NOT NULL,
    content TEXT NOT NULL
);

Boolean and temporal data

CREATE TABLE book (
    isbn CHAR(13) NOT NULL,
    author_first_name VARCHAR(50) NOT NULL,
    author_last_name VARCHAR(50) NOT NULL,
    content TEXT NOT NULL,
    originally_published DATE NOT NULL,
    out_of_print BOOLEAN DEFAULT FALSE
);

The BOOLEAN data type

Three possible values
- true state
- false state
- NULL (unknown state)
Common for representing yes-or-no scenarios
Can be defined with keyword BOOL or BOOLEAN

in_stock BOOL DEFAULT TRUE;

Temporal data types

Type	Descriptions	Format
`TIMESTAMP`	represents a date and time	2010-09-21 15:47:16
`DATE`	represents a date	1972-07-08
`TIME`	represents a time	05:30:00

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Creating PostgreSQL Databases