Can I mix MySQL APIs in PHP? -

i have searched net , far have seen can use mysql_ , mysqli_ meaning:

<?php $con=mysqli_connect("localhost", "root" ,"" ,"mysql");  if( mysqli_connect_errno( $con ) ) {     echo "failed connect"; }else{     echo "connected"; } mysql_close($con); echo "done"; ?> 

or

<?php $con=mysql_connect("localhost", "root" ,"" ,"mysql"); if( mysqli_connect_errno( $con ) ) {     echo "failed connect"; }else{     echo "connected"; } mysqli_close($con); echo "done"; ?> 

are valid when use code is:

connected warning: mysql_close() expects parameter 1 resource, object given in d:\************.php on line 9 done 

for first , same except mysqli_close(). second one.

what problem? can't use mysql_ , mysqli together? or normal? way can check if connections valid @ all? (the if(mysq...))

no, can't use mysql , mysqli together. separate apis , resources create incompatible 1 another.

there mysqli_close, though.