Php MySQLi相当于MySQL代码
你能给我这个代码的等价物吗?我做不好Php MySQLi相当于MySQL代码,php,mysql,mysqli,Php,Mysql,Mysqli,你能给我这个代码的等价物吗?我做不好 <?php if(mysql_num_rows(mysql_query("SELECT userid FROM users WHERE userid = '$userid'"))){ //code to be exectued if user exists } ?> 我会这样做: $connection = mysqli_connect(...); $result = mysqli_query( $connection, "SE
<?php
if(mysql_num_rows(mysql_query("SELECT userid FROM users WHERE userid = '$userid'"))){
//code to be exectued if user exists
}
?>
我会这样做:
$connection = mysqli_connect(...);
$result = mysqli_query(
$connection,
"SELECT COUNT(*) AS cnt FROM users WHERE userid = '$userid'"
) or die(mysqli_error()); //use proper error handling here: or die() used for brevity
$row = mysqli_fetch_assoc($result);
if($row['cnt'] > 0) {
//do your thing
}
从面向对象的意义上讲,它将来自:
if(mysql_num_rows(mysql_query("SELECT userid FROM users WHERE userid = '$userid'"))){
//code to be exectued if user exists
}
到(假定为数字用户ID):
到(假定字符串用户ID):
至(假设准备好的报表):
现在,假设您使用的是MySQLi的OOP版本(IMHO,您应该这样做,因为它在很多方面使生活更轻松) 我会这样做:
$result = $mysqli->query("SELECT userid FROM users WHERE userid = '$userid'");
$row = mysqli_fetch_assoc($result);
if ($row['userid'] > 0 ) {
echo "<h1>AWESOME</h1>";
}
$result=$mysqli->query(“从userid='$userid''的用户中选择userid”);
$row=mysqli\u fetch\u assoc($result);
如果($row['userid']>0){
呼应“真棒”;
}
不行,我的朋友。在问之前试过:)@WideBlade:那你为什么不在问题中陈述呢?那一定是出了什么问题,但你给我们的信息太少了。您是否收到任何错误消息?$connection实际上是一个mysqli链接资源吗?确实是。您能告诉我一种不同的方法来发现数据库中是否存在用户吗?这是正确的方法。你只是做错了什么,不想让我们帮你。你可以通过一个额外的查询select FOUND\u ROWS()来完成。你也可以用鼻子喝牛奶!哦,上校回来了。想念你。@Col:更新了。好的一点,我只是假设它是一个int(愚蠢,我知道),我会留下一个例子only@ircmaxell-谢谢@上校,谢谢@你的问题是?
if(mysql_num_rows(mysql_query("SELECT userid FROM users WHERE userid = '$userid'"))){
//code to be exectued if user exists
}
$result = $mysqli->query("SELECT userid FROM users WHERE userid = ".(int) $userid);
if ($result->num_rows) {
//code
}
$result = $mysqli->query("SELECT userid FROM users WHERE userid = '". $db->real_escape_string($userid) . "');
if ($result->num_rows) {
//code
}
$stmt = $mysqli->prepare("SELECT userid FROM users WHERE userid = ?");
$stmt->bind_param('s', $userid);
$stmt->execute();
$stmt->store_result();
if ($stmt->num_rows) {
//code
}
$result = $mysqli->query("SELECT userid FROM users WHERE userid = '$userid'");
$row = mysqli_fetch_assoc($result);
if ($row['userid'] > 0 ) {
echo "<h1>AWESOME</h1>";
}