Preamble
PostgreSQL Comparison Operators are used in the WHERE sentence to determine which entries to choose. Here is a list of comparison statements that you can use in PostgreSQL :
Comparison operators
|
Description
|
---|---|
=
|
Equally
|
<>
|
Does not matter
|
!=
|
Does not matter
|
>
|
More than
|
>=
|
More or equal
|
<
|
Less than
|
<=
|
Less or equal
|
IN ()
|
Corresponds to the value in the list
|
NOT
|
Denies condition
|
BETWEEN
|
Within range (inclusive)
|
IS NULL
|
value NULL
|
NOT NULL
|
Not NULL value
|
LIKE
|
Comparison with % and _ pattern
|
EXISTS
|
Condition fulfilled if the subquery returns at least one line
|
Consider comparison operators that you can use in PostgreSQL.
Example – operator =
In PostgreSQL, you can use the = operator to check for equality in a query.
For example, you can use an = operator:
SELECT *
FROM empls
WHERE first_name = 'Frog';
In this example, the SELECT statement above returns all rows from the employee table, where first_name equals Frog.
Example – operator =
There are two ways to check inequality in PostgreSQL. You can use the <> or != operator.
For example, we can check for inequality using the <> operator in the following way :
In this example, the SELECT operator above returns all rows from the employee table, where first_name equals Frog.
An example is the – operator
There are two ways to check inequality in PostgreSQL. You can use the <> or != operator.
For example, we can check for inequality using the <> operator in the following way :
SELECT *
FROM empls
WHERE first_name <> 'Frog';
In this example, the SELECT statement returns all rows from the employee table where first_name does not equally Frog.
Or you can also write this query using the != operator as shown below :
SELECT *
FROM empls
WHERE first_name != 'Frog';
Both these requests will return the same results.
Example – operator =
You can use the > operator in PostgreSQL to check the expression for more than that.
SELECT *
FROM products
WHERE product_id > 50;
In this example, the SELECT operator will return all rows from the products table where product_id is over 50. a product_id equal to 50 will not be included in the result set.
Example – the <= operator
In PostgreSQL, you can use the >= operator to check whether the expression is larger or equal.
SELECT *
FROM products
WHERE product_id >= 50;
In this example, the SELECT operator will return all rows from the products table where product_id is greater than or equal to 50. In this case, a product_id equal to 50 will be included in the result set.
The example is the operator <
You can use the < statement in PostgreSQL to check the expressionless.
SELECT *
FROM inventory
WHERE inventory_id < 25;
In this example, the SELECT operator will return all rows from the inventory table where inventory_id is less than 25. An inventory_id value of 25 will not be included in the result set.
Example – operator <
In PostgreSQL, you can use the <= operator to test an expression that is less than or equal.
SELECT *
FROM inventory
WHERE inventory_id <= 25;
In this example, the SELECT operator will return all rows from the inventory table where inventory_id is less than or equal to 25. In this case, n inventory_id value 25 will be included in the result set.
PostgreSQL: Comparison Operators | Course
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