php - can't connect to db in my sql -

i using mamp on mac connect localhost ,i can connect server problem cant connect db, don't know in part of query making mistake since 1 line query.i searched different solutions here on stack overflow couldnt helpful

$username = 'root'; $password = 'root'; $host     = 'localhost'; $database = 'trendnow'; $link = mysqli_connect($host, $username, $password);   if (!$link) { echo 'can not connect server'; } $db_selected = mysqli_select_db($database,$link); echo $db_selected; if (!$db_selected) {   echo 'can not connect trend '; } 

felippe duarte correct. database trying connect to?

mysqli_connect("localhost","my_user","my_password","my_db"); 

• localhost means connect server program running on. people connect database located on server not local, ip address.
• my_db name of database. if database called webstore, may have table located on database called, computers. webstore name of database , must reside in last section, so: mysqli_connect("localhost","my_user","my_password","webstore");

here tutorial may help. http://www.w3schools.com/php/func_mysqli_connect.asp

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getting useful error message

the problem stand alone connection if there error, won't tell is. thankfully there few ways find out error is.

<?php     $con = mysqli_connect("localhost","my_user","my_password","my_db");  //this check if able start connection using above line if (mysqli_connect_errno()) {   echo "failed connect mysql: " . mysqli_connect_error(); }  // example query. check if failed, , if so, why failed // perform query, check error if (!mysqli_query($con,"insert persons (firstname) values ('glenn')")) {   echo("error description: " . mysqli_error($con)); }  ?> 

http://www.w3schools.com/php/func_mysqli_error.asp