PHP connection MYSQL database instance code

<?php
//Set the character setheader('Content-Type: text/html; charset=utf8');
//Connect the database$link = mysql_connect("localhost","root","123456");
if(!$link){
echo 'Database connection failed...<br>';
exit(-1);
}else{
echo "The database connection is successful...<br>";
}
//Select a database as the default databasemysql_select_db('php_sjk');
//Execute SQL insertion statement$sql = "INSERT INTO zh VALUES (NULL,'Wang Jie','123456')";
$cr = mysql_query($sql);
//Judge whether the insertion is successfulif(!$cr){
echo "Data insertion failed.<br>";
}else{
echo "Data insertion successfully.<br>";
}
//Execute SQL query statement$sql = "select * from zh";
$cr = mysql_query($sql);
//Get the returned result set and loop the outputecho "Data Display: <br><br><br>";
while($a = mysql_fetch_row($cr)){
echo "{$a[0]}——{$a[1]}——{$a[2]}&lt;br&gt;";
}
//Close the database connectionmysql_close($link);
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