插入语句不起作用，没有错误

var lid = $('#lid').val();
$.ajax({
        type:"post",
        url:'../library/lib.php',
        data:'action=save_memo&lid'+lid,

        success:function(response){
            console.log(response);

        }

here is the content of lib.php

switch($action){
    case 'save_memo':
        save_memo($_POST['lid']);
        break;}

function save_memo($lid){
    $insert = "INSERT INTO tbl_memo (id) VALUES ('$lid')";

    if(mysql_query($insert) == false){
        $result = array("failed" => $insert)
    }else{
       $result = array("sucess" => $insert);
       echo json_encode($result);
    }

the response is success but it doesnt insert into the database
please someone tell me what's wrong, thanks in advance

I believe you're missing an = sign in your jQuery call:

data:'action=save_memo&lid'+lid

Should be:

data:'action=save_memo&lid='+lid,

Also, check out the big red warning on the mysql_query manual page:

Warning

This extension is deprecated as of PHP 5.5.0, and will be removed in the future. Instead, the MySQLi or PDO_MySQL extension should be used. See also MySQL: choosing an API guide and related FAQ for more information. Alternatives to this function include:

• mysqli_query()
• PDO::query()

1. Your are posting the variable action with content save_memo+[lid]. So when you attempt to retrieve $_POST['lid'], you will get save_memo concatenated with whatever the value of #lid is.
2. You do not retrieve the variable $action before attempting to evaluate it with the switch statement.
3. $lid is not a variable that was posted with the AJAX request, $action was.