防止重复的行数据条目

Question

I had created a database which named student with ID, name, mat_number, specialty, age, and gender, in a PHP application.

I do not want the name or mat_number be taken in more than once.

I have done the connection to my database in a different page and called it in the add student page.

This following codes is for a faculty database collection

    <?php 
                if(isset($_POST['submit']))  {
                    $name = $_POST['name'];
                    $matNo = $_POST['mat_number'];
                    $age = $_POST['age'];
                    $specialty = $_POST['specialty'];
                    $gender = $_POST['gender'];

                    if(!empty($name) && !empty($matNo) && !empty($age) && 
                            !empty($specialty) && !empty($gender))
                {

                    $sql = "INSERT INTO `student`(`name`, `UB_number`, `age`, 
                                          `sex`, `specialty`)
                    VALUES ('$name', '$matNo', '$age', '$gender', '$specialty')";
                    $conn->query($sql);
                    header("Location: index.php");
                }
                else{
                    echo "Error: Complete all records";
                }          
                }

            ?>

I want to get an error message demanding for a change if the 2 fields already exist in the database.

Answer 1

hope this may be helpfull to you. In here I asume that you are not using any framework. But if you use a framework there are plenty of easy methods to do this.In here I have checked only name field. You should update code as you wants. Also it it better if you could validate your inputs before check. Like trim(). Thanks

<?php 
            if(isset($_POST['submit']))  {

                $name = $_POST['name'];
                $matNo = $_POST['mat_number'];
                $age = $_POST['age'];
                $specialty = $_POST['specialty'];
                $gender = $_POST['gender'];

                //after user click the submit button 
                $sql_Select_Stundets = "SELECT * FROM student WHERE name = '$name' ";
                 // query the sql with db connection         
                $result_sql_Select_Stundets = mysqli_query($conn,$sql_Select_Stundets);
                //Now check the row count to verify the output if there is any match
                $rowcount=mysqli_num_rows($result);

                //Now write insert inside if condition
                 if( $rowcount >0 ) {

                    if(!empty($name) && !empty($matNo) && !empty($age) && 
                    !empty($specialty) && !empty($gender)) {

                    $sql = "INSERT INTO `student`(`name`, `UB_number`, `age`, 
                                  `sex`, `specialty`)
                    VALUES ('$name', '$matNo', '$age', '$gender', '$specialty')";
                    $conn->query($sql);
                    bheader("Location: index.php");
                }else{

                    echo "Error: Complete all records";
                     }    

                }else{
                       echo "<script>
                       alert('sorry this name is already available');
                        </script>";
                    }

                 }              
        ?>