what does where mean in mysql

The WHERE keyword is used to specify conditions to filter MySQL query results and only return rows that meet the conditions. Syntax: SELECT ... FROM table_name WHERE condition. You can specify conditions using logical operators (AND, OR, NOT) and comparison operators (=, !=, <, <=, >, >=). The wildcard character (%) matches zero or more characters, and (_) matches a single character. The WHERE clause can also be used to sort, group, and aggregate results.

WHERE keyword

The WHERE keyword is used to specify conditions in a MySQL query to filter the results of the query , only return rows that meet the conditions.

Syntax

<code class="sql">SELECT ...
FROM table_name
WHERE condition</code>

How to use

In the WHERE clause, the condition specifies the data value to be applied to the row . Conditions can be simple comparisons, logical operators, or more complex expressions.

Example

The following query returns all persons with the name "John Doe":

<code class="sql">SELECT *
FROM people
WHERE name = "John Doe"</code>

Logical operators

Logical operators can be used to combine conditions:

• AND: Returns the behavior when all conditions are true.
• OR: Returns the behavior when either condition is true.
• NOT: Returns the behavior when the condition is false.

The following query returns all persons older than 25 years old who are in the male table:

<code class="sql">SELECT *
FROM people
WHERE age > 25 AND gender = "male"</code>

Comparison Operator

Comparison Operator Used to compare data values:

• =: equal to
• <> or !=: not equal to
• <: less than
• <=: less than or equal to

• : greater than

• =: greater than or equal to

## Wildcard character

Wildcard character can be used to match some data values:

%: matches zero or more characters.
• _: Matches a single character.

The following query returns all names starting with "J":

<code class="sql">SELECT *
FROM people
WHERE name LIKE "J%"</code>

Other usage

The WHERE clause can also be used for the following operations :

Sort the results.
• Group results.
• Aggregation results.

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