新版本PHP使用更方便了

$hostname_conn = "";
$database_conn = "";
$username_conn = "root";
$password_conn = "";
$conn =mysqli_connect($hostname_conn, $username_conn, $password_conn, $database_conn);

<?php
$con=mysqli_connect("localhost","my_user","my_password","my_db");
// Check connection
if (mysqli_connect_errno($con))
{
echo "Failed to connect to MySQL: " . mysqli_connect_error();
}

// Perform queries 
mysqli_query($con,"SELECT * FROM Persons");
mysqli_query($con,"INSERT INTO Persons (FirstName,LastName,Age) 
VALUES ('Glenn','Quagmire',33)");

mysqli_close($con);
?>

<?php
$con=mysqli_connect("localhost","my_user","my_password","my_db");
// Check connection
if (mysqli_connect_errno($con))
{
echo "Failed to connect to MySQL: " . mysqli_connect_error();
}

$sql="SELECT Lastname,Age FROM Persons ORDER BY Lastname";
$result=mysqli_query($con,$sql)

// Associative array
$row=mysqli_fetch_assoc($result);
printf ("%s (%s)n",$row["Lastname"],$row["Age"]);

// Free result set
mysqli_free_result($result);

mysqli_close($con);
?>

php mysqli query 查询数据库后读取内容的方法

<?php
$mysqli = new mysqli("localhost", "my_user", "my_password", "world");

/* check connection */
if ($mysqli->connect_errno) {
    printf("Connect failed: %s\n", $mysqli->connect_error);
    exit();
}

/* Create table doesn't return a resultset */
if ($mysqli->query("CREATE TEMPORARY TABLE myCity LIKE City") === TRUE) {
    printf("Table myCity successfully created.\n");
}

/* Select queries return a resultset */
if ($result = $mysqli->query("SELECT Name FROM City LIMIT 10")) {
    printf("Select returned %d rows.\n", $result->num_rows);

/* free result set */
    $result->close();
}

/* If we have to retrieve large amount of data we use MYSQLI_USE_RESULT */
if ($result = $mysqli->query("SELECT * FROM City", MYSQLI_USE_RESULT)) {

/* Note, that we can't execute any functions which interact with the
       server until result set was closed. All calls will return an
       'out of sync' error */
    if (!$mysqli->query("SET @a:='this will not work'")) {
        printf("Error: %s\n", $mysqli->error);
    }
    $result->close();
}

$mysqli->close();
?>

实例代码：

$sql="select * from qa limit 0,10";
 $result=$mysqli->query($sql);
 while ($row = mysqli_fetch_assoc($result))
  {
    echo "question_title : {$row['question_title']} <br>";
    echo "answer_content1: {$row['answer_content1']} <br>";
  }
 /* free result set */
    $result->close();