【PHP】mysql基本操作整合

<?php
function connetionDB($servername, $username, $password, $db) {
   // 创建连接$conn = mysqli_connect($servername, $username, $password, $db);

    // 检测连接if (!$conn) {
        die("Connection failed: " . mysqli_connect_error());
        returnFALSE;
    }
    return$conn;
}

//创建数据库function create_db($dbname, $conn) {
     $sql = "create database ‘$dbname‘";
     if(mysqli_query($conn, $sql)) {
         echo "DB created successfully";
     }else {
         echo "Error: ".mysqli_error($conn);
     }
}


//新建表function create_table($conn) {
    $sql = "CREATE TABLE Account (
     id INT(6) UNSIGNED AUTO_INCREMENT PRIMARY KEY,
     username VARCHAR(30) NOT NULL,
     password VARCHAR(30) NOT NULL
     )";

    if(mysqli_query($conn, $sql)) {
        echo "table created successfully";
    }else{
        echo "Error: ".mysqli_error($conn);
    }
}

//插入数据function insert($username, $password, $conn){
    $sql = "insert into Account (username, password) values (‘$username‘, ‘$password‘)";
    if(mysqli_query($conn, $sql)) {
        echo "Insert successfully<br>";
    }else{
        echo "Error:" . mysqli_error($conn);
    }
}

//查询数据function get($username, $conn) {
    $sql = "SELECT password FROM Account WHERE username = ‘$username‘";
    $result = mysqli_query($conn, $sql);
    if (!$result) {
        printf("Error: %s\n", mysqli_error($conn));
        exit();
    }
    while($row = mysqli_fetch_array($result)) {
//        echo "username: " . $username ." password : " . $row[‘password‘];
//        echo "<br>";return$row[‘password‘];
    }

}

//删除数据function delete($username, $password, $conn) {
    $sql = "DELETE FROM Account WHERE username = ‘$username‘ and password = ‘$password‘";
    if(mysqli_query($conn, $sql)) {
        echo "Delete $username successfully<br>";
    }else{
        echo "Error:" . mysqli_error($conn);
    }
}

//更新数据function update($username, $password, $new_username, $new_password, $conn) {
    $sql = ‘‘;
    if($new_username == ‘‘ and $new_password != ‘‘) {
        $sql = "UPDATE Account SET password = ‘$new_password‘ WHERE username = ‘$username‘ AND password = ‘$password‘";
    }elseif($new_username != ‘‘ and $new_password == ‘‘){
        $sql = "UPDATE Account SET username = ‘$new_username‘ WHERE username = ‘$username‘ AND password = ‘$password‘";
    }elseif($new_username != ‘‘ and $new_password != ‘‘){
        $sql = "UPDATE Account SET username = ‘$new_username‘, password = ‘$new_password‘ WHERE username = ‘$username‘ AND password = ‘$password‘";
    }
    if(mysqli_query($conn, $sql)) {
//        echo "Update successfully";returntrue;
    }else {
//        echo "Error : " . mysqli_error($conn);returnfalse;
    }
}

//关闭连接function closeDB($conn) {
    mysqli_close($conn);
}