问题描述
提交时(ID、用户名、分数),如果分数高于用户名之前的分数,我只希望数据库更新。
到目前为止我有
$sql = MysqLi_query($con,"INSERT INTO $db_name.$db_table (ID,name,score)
VALUES ((ID,score) IF $ID=ID & $name=name & '$score'>score);");
完整代码是
if(isset($_GET['ID']) & isset($_GET['name']) & isset($_GET['score'])){
$con = MysqLi_connect($host,$db_username,$db_password,$db_name);
$ID = strip_tags(MysqLi_real_escape_string($con,$_GET['ID']));
$name = strip_tags(MysqLi_real_escape_string($con,$_GET['name']));
$score = strip_tags(MysqLi_real_escape_string($con,$_GET['score']));
$sql = MysqLi_query($con,score)
VALUES ((ID,score) IF $ID=ID & $name=name & '$score'>score);");
if($sql){
//The query returned true - Now do whatever you like here.
echo 'Your score was saved. Congrats!';
}else{
//The query returned false - you might want to put some sort of error reporting here. Even logging the error to a text file is fine.
echo("<br>Error description: " . MysqLi_error($con));
}
MysqLi_close($con);//Close off the MysqLI connection to save resources.
解决方法
您似乎想要on duplicate key update
。您需要每个 name
一行,因此您需要一个唯一的索引或名称的约束:
CREATE UNIQUE INDEX unq_table_name ON $db_name.$db_table(name);
然后你可以使用:
INSERT INTO $db_name.$db_table (ID,name,score)
VALUES (ID,score)
ON DUPLICATE KEY UPDATE score = GREATEST(score,VALUES(score));
$db_name.$db_table
的使用存在很大问题。它表明单个实体(表中应有的任何内容)分布在多个表中。这真的很糟糕数据建模。
此外,它可能会导致代码被 SQL 注入并难以调试语法错误。我建议您重新考虑您的数据库设计,以便您只在一张表中获得分数,可能称为 user_scores
或比 $db_name.$db_table
更易于理解的名称。