What potential issues can arise when using inner and outer joins in SQL queries in PHP?

One potential issue when using inner and outer joins in SQL queries in PHP is that it can result in duplicate rows being returned if the join conditions are not properly specified. To solve this issue, you can use the DISTINCT keyword in your SQL query to remove any duplicate rows from the result set. 

$query = "SELECT DISTINCT column1, column2 
          FROM table1 
          INNER JOIN table2 ON table1.id = table2.id";

$result = mysqli_query($connection, $query);

if(mysqli_num_rows($result) > 0) {
    while($row = mysqli_fetch_assoc($result)) {
        // Process the data
    }
} else {
    echo "No results found.";
}

Keywords

SQL queries inner join outer join PHP database connectivity

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