php-mysqlHow to use a MySQL union in PHP?

MySQL UNION is a powerful operator used to combine the result sets of two or more SELECT statements into a single result set. It can be used in PHP to retrieve data from multiple tables in a single query.

Example code

$sql = "SELECT * FROM table1
        UNION
        SELECT * FROM table2";
$result = mysqli_query($conn, $sql);

Output example

Array
(
    [0] => Array
        (
            [id] => 1
            [name] => John
            [age] => 25
        )

    [1] => Array
        (
            [id] => 2
            [name] => Jane
            [age] => 30
        )

)

Code explanation

1. $sql: This is the SQL query that contains the UNION operator.
2. mysqli_query($conn, $sql): This is the function used to execute the query. $conn is the connection to the MySQL database.
3. UNION: This is the operator used to combine the result sets of two or more SELECT statements into a single result set.
4. SELECT * FROM table1: This is the first SELECT statement used to retrieve data from the first table.
5. SELECT * FROM table2: This is the second SELECT statement used to retrieve data from the second table.

Helpful links

1. MySQL UNION Operator
2. MySQLi Query

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