MySQL DISTINCT statement.

Preamble

MySQL DISTINCT statement is used to remove duplicates from the result set. The DISTINCT operator may be used only with SELECT operators.

Syntax DISTINCT operator in MySQL

SELECT DISTINCT
FROM tables
[WHERE conditions];

Parameters and arguments of the operator

• expressions – columns or calculations that you want to get.
• tables – the tables from which you want to get the records. There must be at least one table listed in the FROM statement.
• WHERE conditions are optional. The conditions that must be met for the selected records.

Note:

• When only one expression is provided in DISTINCT, the query returns unique values for this.
• If more than one expression is present in DISTINCT, the query will receive unique combinations for the specified expressions.
• In MySQL, the DISTINCT operator does not ignore NULL values. Therefore when using DISTINCT in your SQL offer, your resulting set will include NULL as a separate value.

One-column example

Let’s consider a simple example of MySQL statement DISTINCT. We can use MySQL DISTINCT to return a single column that removes duplicates from the result set.

For example:

SELECT DISTINCT state
FROM customers;

This example MySQL DISTINCT returns all unique state values from the customer’s table.

Example with multiple columns

Let’s look at an example of how you can use the MySQL DISTINCT statement to remove duplicates from more than one column in a SELECT statement.
For example:

SELECT DISTINCT city, state
FROM customers;

This example of a DISTINCT MySQL statement returns each unique combination of city and state fields from the Customers table. In this case, DISTINCT applies to each column specified after the DISTINCT keyword and therefore returns individual combinations.

MySQL Tutorial for Beginners; MySQL SELECT DISTINCT Statement

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