What common syntax errors should PHP developers be aware of when creating SQL queries?

One common syntax error that PHP developers should be aware of when creating SQL queries is forgetting to properly escape strings to prevent SQL injection attacks. This can be solved by using prepared statements with parameterized queries instead of directly inserting user input into the SQL query. 

// Incorrect way without prepared statements
$user_input = $_POST['username'];
$query = "SELECT * FROM users WHERE username = '$user_input'";
$result = mysqli_query($connection, $query);

// Correct way using prepared statements
$user_input = $_POST['username'];
$query = "SELECT * FROM users WHERE username = ?";
$stmt = mysqli_prepare($connection, $query);
mysqli_stmt_bind_param($stmt, "s", $user_input);
mysqli_stmt_execute($stmt);
$result = mysqli_stmt_get_result($stmt);

Keywords

SQL injection syntax errors mysqli_real_escape_string prepared statements query validation

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