Summary: in this tutorial, you will learn about the PostgreSQL BOOL_OR() function to aggregate boolean values across rows within a group.

Introduction to the PostgreSQL BOOL_OR() function

The BOOL_OR() is an aggregate function that allows you to aggregate boolean values across rows within a group.

Here’s the syntax of the BOOL_OR() function:

bool_or(expression)

In this syntax, the expression is the boolean expression to evaluate.

The BOOL_OR() function returns true if at least one value in the group is true. If all values are false, the function returns false.

Please note that the BOOL_OR function ignores NULLs within the group.

PostgreSQL BOOL_OR() function examples

Let’s explore some examples of using the BOOL_OR() function.

1) Setting up sample tables

First, create tables called teams and members:

CREATE TABLE teams (
    team_id SERIAL PRIMARY KEY,
    team_name VARCHAR(100) NOT NULL
);

CREATE TABLE members (
    member_id SERIAL PRIMARY KEY,
    member_name VARCHAR(100) NOT NULL,
    active bool,
    team_id INT REFERENCES teams(team_id)
);

Second, insert rows into the tables:

INSERT INTO teams (team_name)
VALUES
('Team A'),
('Team B'),
('Team C')
RETURNING *;

INSERT INTO members (member_name, team_id, active)
VALUES
('Alice', 1, true),
('Bob', 2, true),
('Charlie', 1, null),
('David', 2, false),
('Peter', 3, false),
('Joe', 3, null)
RETURNING *;

The teams table:

team_id | team_name
---------+-----------
       1 | Team A
       2 | Team B
       3 | Team C
(3 rows)

The members table:

member_id | member_name | active | team_id
-----------+-------------+--------+---------
         1 | Alice       | t      |       1
         2 | Bob         | t      |       2
         3 | Charlie     | null   |       1
         4 | David       | f      |       2
         5 | Peter       | f      |       3
         6 | Joe         | null   |       3
(6 rows)

2) Basic BOOL_OR() function example

The following example uses the BOOL_OR() function to test if there are any active members in the members table:

SELECT
  BOOL_OR(active) active_member_exists
FROM
  members;

Output:

active_member_exists
----------------------
 t
(1 row)

The BOOL_OR() function returns true indicating that the members table has active members.

2) Using BOOL_OR() function with GROUP BY clause

The following example uses the BOOL_OR() function with the GROUP BY clause to check if there are any active members in each team:

SELECT
  team_name,
  BOOL_OR(active) active_member_exists
FROM
  members
  INNER JOIN teams USING (team_id)
GROUP BY
  team_name;

Output:

team_name | active_member_exists
-----------+----------------------
 Team A    | t
 Team B    | t
 Team C    | f
(3 rows)

The output indicates that teams A and B have active members whereas team C does not have any active members.

3) Using BOOL_OR() function in HAVING clause

The following example uses the BOOL_OR() function with the GROUP BY and HAVING clauses to retrieve teams that have active members:

SELECT
  team_name,
  BOOL_OR(active) active_member_exists
FROM
  members
  INNER JOIN teams USING (team_id)
GROUP BY
  team_name
HAVING
  BOOL_OR(active) = true;

Output:

team_name | active_member_exists
-----------+----------------------
 Team A    | t
 Team B    | t
(2 rows)

Summary

  • Use the BOOL_OR() function to aggregate boolean values across rows within a group.
  • The BOOL_OR() function ignores NULLs in the group.