PostgreSQL min function.

Preamble

The min function in PostgreSQL returns the minimum value of the expression.

Syntax of the min function in PostgreSQL

SELECT min(aggregate_expression_id)
FROM tabs
[WHERE conds];

Or the syntax of the min function when grouping the results into one or more columns:

SELECT expression1_id,2_id,..._n_id,
min(aggregate_expression_id)
FROM tabs
[WHERE conds]
GROUP BY expression1_id,2_id,..._n_id;

Parameters and arguments of the function

• expression1_id, expression2_id,… expression_n_id – Expressions that are not enclosed in the min function and must be included in the GROUP BY operator at the end of the SQL query.
• aggregate_expression_id – This is a column or expression from which the minimum value will be returned.
• tabs – These are the tables from which you want to get the records. At least one table must be specified in the FROM operator.
• WHERE conds – Optional. These are the conditions that must be met to select records.

The min function can be used in the following PostgreSQL versions

PostgreSQL 11, PostgreSQL 10, PostgreSQL 9.6, PostgreSQL 9.5, PostgreSQL 9.4, PostgreSQL 9.3, PostgreSQL 9.2, PostgreSQL 9.1, PostgreSQL 9.0, PostgreSQL 8.4.

Single Expression Example

Consider some examples of min functions to understand how to use the min function in PostgreSQL.
For example, you can find out how the minimum value is in the inventory table.

SELECT min(quantity) AS "Lowest Quantity"
FROM inventory;

In this example of the min function, we called the expression min(quantity) as “Lowest Quantity”. As a result, “Lowest Quantity” will be displayed as the field name when the result set returns.

Example using GROUP BY

In some cases, you will need to use GROUP BY operator with min function.
For example, you can also use the min function to return values in the department field and the min(quantity) field from the inventory table.

SELECT department, min(quantity) AS "Lowest Quantity"
FROM inventory
GROUP BY department;

Since your SELECT operator has one column that is not encapsulated in the min function, you must use the GROUP BY operator. That is why the department field should be specified in the GROUP BY operator.

PostgreSQL: Calculating Min, Max; Average

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