> ## Documentation Index > Fetch the complete documentation index at: https://villagesql.com/docs/llms.txt > Use this file to discover all available pages before exploring further. # MySQL operators > The comparison and arithmetic operators MySQL uses in a select list, what a comparison returns, which ones bind tighter, and how NULL behaves against them. All examples on this page work on VillageSQL. Install Now → Operators combine values into a new value. You have already used one: the `*` in `rental_rate * 1.1`. This lesson covers the everyday set, and the one behavior that catches everybody, which is what happens when `NULL` turns up. Open the client with `mysql -u root -p sakila` before you start. ## How an operator works ```sql theme={null} SELECT LEFT_VALUE OPERATOR RIGHT_VALUE; ``` Replace `LEFT_VALUE` and `RIGHT_VALUE` with values and `OPERATOR` with one of the symbols below. A value can be a column, or it can be a literal, meaning a number or a piece of text written directly into the statement. A `SELECT` with no `FROM` evaluates its expressions and returns a single row, which makes it the quickest way to try an operator out. ## Examples ### 1) Comparison returns 1 or 0 MySQL has no distinct boolean type. A comparison that holds returns the integer `1`, and one that does not returns `0`. The words `TRUE` and `FALSE` are spellings of those 2 integers. ```sql theme={null} SELECT 1 = 1, 1 <> 2, 1 != 2, 2 > 3, 3 >= 3, 2 <= 2; ``` ```text theme={null} +-------+--------+--------+-------+--------+--------+ | 1 = 1 | 1 <> 2 | 1 != 2 | 2 > 3 | 3 >= 3 | 2 <= 2 | +-------+--------+--------+-------+--------+--------+ | 1 | 1 | 1 | 0 | 1 | 1 | +-------+--------+--------+-------+--------+--------+ 1 row in set (0.00 sec) ``` Equality is a single `=`, not the double `==` that most programming languages use. `<>` and `!=` both mean not equal and behave identically. This tutorial writes `<>`. ### 2) Arithmetic, and which operator binds tighter ```sql theme={null} SELECT 2 + 3 * 4, (2 + 3) * 4, 7 / 2, 7 DIV 2, 7 % 2; ``` ```text theme={null} +-----------+-------------+--------+---------+-------+ | 2 + 3 * 4 | (2 + 3) * 4 | 7 / 2 | 7 DIV 2 | 7 % 2 | +-----------+-------------+--------+---------+-------+ | 14 | 20 | 3.5000 | 3 | 1 | +-----------+-------------+--------+---------+-------+ 1 row in set (0.00 sec) ``` `2 + 3 * 4` is 14, so multiplication happened first. Brackets override that and make it 20. `/` gives a decimal result even between 2 whole numbers, `DIV` throws the fraction away, and `%` gives the remainder. ### 3) DIV and % bind as tightly as division ```sql theme={null} SELECT 10 - 4 / 2, 10 - 4 DIV 2, 1 + 7 % 3; ``` ```text theme={null} +------------+--------------+-----------+ | 10 - 4 / 2 | 10 - 4 DIV 2 | 1 + 7 % 3 | +------------+--------------+-----------+ | 8.0000 | 8 | 2 | +------------+--------------+-----------+ 1 row in set (0.00 sec) ``` All 3 give the answer you get by doing the division or the remainder first. If `-` bound tighter than `/`, the first column would be 3 rather than 8. ### 4) Operators work on columns Anything you can do to a literal you can do to a column. ```sql theme={null} SELECT title, length, length > 100 AS is_long FROM film ORDER BY title; ``` ```text theme={null} +-----------------------------+--------+---------+ | title | length | is_long | +-----------------------------+--------+---------+ | ACADEMY DINOSAUR | 86 | 0 | | ACE GOLDFINGER | 48 | 0 | | ADAPTATION HOLES | 50 | 0 | | AFFAIR PREJUDICE | 117 | 1 | | AFRICAN EGG | 130 | 1 | ... +-----------------------------+--------+---------+ 1000 rows in set (0.00 sec) ``` The comparison becomes a column of 1s and 0s, and the alias gives it a name. ## NULL is not equal to anything, including NULL You met `NULL` in the sorting lesson as the marker for a value that was never recorded. It behaves unlike any real value here. ```sql theme={null} SELECT NULL = NULL, NULL <> NULL, NULL <=> NULL, 1 <=> NULL; ``` ```text theme={null} +-------------+--------------+---------------+------------+ | NULL = NULL | NULL <> NULL | NULL <=> NULL | 1 <=> NULL | +-------------+--------------+---------------+------------+ | NULL | NULL | 1 | 0 | +-------------+--------------+---------------+------------+ 1 row in set (0.00 sec) ``` Asking whether one unrecorded value equals another cannot be answered, so `NULL = NULL` returns `NULL` rather than 1 or 0. So does `NULL <> NULL`. Every operator in example 1 behaves that way against `NULL`. `<=>` is the exception. It compares 2 values and always returns 1 or 0, never `NULL`, treating `NULL` as equal to itself. The consequence is that `= NULL` matches nothing, ever. When you need to find the rows where a value is absent, [IS NULL](/docs/tutorial/is-null) is the test, and it returns 1 or 0 like an ordinary comparison. ## Summary * Expect `1` or `0` back from a comparison, not true or false. * Use `=` for equality and `<>` for inequality. * Remember that `*`, `/`, `DIV` and `%` bind tighter than `+` and `-`. * Use `DIV` for whole number division and `%` for the remainder. * Expect `NULL` from any ordinary comparison involving `NULL`, and use `<=>` or `IS NULL` instead. ## See also * [SELECT](/docs/tutorial/select) — where these expressions go * [Column aliases](/docs/tutorial/column-aliases) — naming the column a comparison produces * [NULL in MySQL](/docs/guides/null-in-mysql) — how NULL behaves across the rest of the language