我有一个与此类似的数据结构
+---------+---------+
| id | value |
+---------+---------+
| 1 | value |
1 | value |
| 1 | value |
| 1 | value |
| 1 | value |
| 2 | value |
| 2 | value |
| 2 | value |
| 3 | value |
| 3 | value |
| 3 | value |
| | |
+---------+---------+
我正在尝试更新此表,看起来像这样
+---------+---------+
| id | value |
+---------+---------+
| 1 | value 0 |
1 | value 1 |
| 1 | value 2 |
| 1 | value 3 |
| 1 | value 4 |
| 2 | value 0 |
| 2 | value 1 |
| 2 | value 2 |
| 3 | value 0 |
| 3 | value 1 |
| 3 | value 2 |
| | |
+---------+---------+
为了达到这个目的,我编写了一个看起来像这样的PHP脚本
$query = "select count(*) as count,id, value from foo group by id";
$sql=$con->prepare($query);
$sql->execute();
$sql->setFetchMode(PDO::FETCH_ASSOC);
while($row=$sql->fetch()){
$id[] = $row['id'];
$count[] = $row['count'];
$value[] = $row['value'];
echo "<pre>";
}
$c=array_combine($id, $count);
foreach ($c as $key=>$value){
for($i=0;$i<=$value;$i++){
$postid = $key;
if($i==0){
$multiple = "multiple";
$newvalue= $value;
}
else{
$x=$i-1;
$multiple = "multiple_".$x;
echo $multiple . "<br>";
$query2 = "update foo set value = :multiple";
$sql2=$con->prepare($query2);
$sql2->bindValue(':multiple', $multiple);
$sql2->execute();
}
}
}
问题是代码返回以下结果
+---------+---------+
| id | value |
+---------+---------+
| 1 | value_1 |
1 | value_1 |
| 1 | value_1 |
| 1 | value_1 |
| 1 | value_1 |
| 2 | value_1 |
| 2 | value_1 |
| 2 | value_1 |
| 3 | value_1 |
| 3 | value_1 |
| 3 | value_1 |
| | |
+---------+---------+
谢谢@Shadow
您的查询运行正常,但会返回以下结果
+------+-----------------------------------------------+
| id | value |
+------+-----------------------------------------------+
| 1 | multiple_1_0_0_0_0_0_0_0_0_0_0_0_0_0_0_0_0 |
| 1 | multiple_1_1_1_1_1_1_1_1_1_1_1_1_1_1_1_1_1 |
| 1 | multiple_1_2_2_2_2_2_2_2_2_2_2_2_2_2_2_2_2 |
| 1 | multiple_1_3_3_3_3_3_3_3_3_3_3_3_3_3_3_3_3 |
| 2 | multiple_1_0_0_0_0_0_0_0_0_0_0_0_0_0_0_0_0 |
| 2 | multiple_1_1_1_1_1_1_1_1_1_1_1_1_1_1_1_1_1 |
| 2 | multiple_1_2_2_2_2_2_2_2_2_2_2_2_2_2_2_2_2 |
| 2 | multiple_1_3_3_3_3_3_3_3_3_3_3_3_3_3_3_3_3 |
| 3 | multiple_1_0_0_0_0_0_0_0_0_0_0_0_0_0_0_0_0 |
| 3 | multiple_1_1_1_1_1_1_1_1_1_1_1_1_1_1_1_1_1 |
| 3 | multiple_1_0_0_0_0_0_0_0_0_0_0_0_0_0_0_0_0 |
+------+-----------------------------------------------+
答案 0 :(得分:1)
您可以通过以下方式进行迭代迭代和创建数据:
<?php
$pdo = new PDO('mysql:host=localhost;dbname=test', 'root', '');
$pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
$sth = $pdo->prepare("SELECT * FROM foo");
$sth->execute();
$data = $sth->fetchAll(PDO::FETCH_ASSOC);
$response = array();
foreach ($data as $dataIndex => $dataValue) {
if (!isset($response[$dataValue["id"]]["count"])) {
$response[$dataValue["id"]]["count"] = 0;
} else {
$response[$dataValue["id"]]["count"] ++;
}
$response[$dataValue["id"]]["values"][$dataValue["pid"]] = "value_" . $response[$dataValue["id"]]["count"];
$sth = $pdo->prepare("UPDATE foo SET value = '{$response[$dataValue["id"]]["values"][$dataValue["pid"]]}' WHERE pid = {$dataValue["pid"]}");
$sth->execute();
}
?>
但是尝试使用最少的迭代进行更新,而不是创建尽可能多的数据库查询,例如:
<?php
$pdo = new PDO('mysql:host=localhost;dbname=test', 'root', '');
$pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
$sth = $pdo->prepare("SELECT * FROM foo");
$sth->execute();
$data = $sth->fetchAll(PDO::FETCH_ASSOC);
$response = array();
$update = array();
foreach ($data as $dataIndex => $dataValue) {
$response[$dataValue["id"]]["id"] = $dataValue["id"];
if (!isset($response[$dataValue["id"]]["count"])) {
$response[$dataValue["id"]]["count"] = 0;
} else {
$response[$dataValue["id"]]["count"] ++;
}
$response[$dataValue["id"]]["values"][$dataValue["pid"]] = "value_" . $response[$dataValue["id"]]["count"];
$update[] = "UPDATE foo SET value = '{$response[$dataValue["id"]]["values"][$dataValue["pid"]]}' WHERE pid = {$dataValue["pid"]};";
}
$update = implode("",$update);
$sth = $pdo->prepare($update);
$sth->execute();
?>
答案 1 :(得分:0)
您的更新查询
$query2 = "update foo set value = :multiple";
不包含任何where条件,每次调用此查询时,它都会更新所有记录中的值字段值。
老实说,我不会真的在这个更新中涉及php,它会在更新中使用用户定义的变量和多表连接语法纯粹在sql中完成:
update foo inner join (select @i:=0, @previd:=-1) as a
set foo.value=concat(foo.value,'_',@i:=if(id=@previd,@i+1,0),if(@previd:=id,'',''))
内部联接中的子查询初始化@i和@previd用户定义的变量。 concat函数的第3个参数确定要连接到value
字段的值@i。 concat的第4个参数设置@previd变量并返回一个空字符串,不影响整体连接。不幸的是,我没有访问MySQL来测试查询,但无论如何它应该是一个很好的起点。
更新
OP在更新的问题中声称我提供的查询创建了以下结果集:
+------+-----------------------------------------------+
| id | value |
+------+-----------------------------------------------+
| 1 | multiple_1_0_0_0_0_0_0_0_0_0_0_0_0_0_0_0_0 |
| 1 | multiple_1_1_1_1_1_1_1_1_1_1_1_1_1_1_1_1_1 |
| 1 | multiple_1_2_2_2_2_2_2_2_2_2_2_2_2_2_2_2_2 |
| 1 | multiple_1_3_3_3_3_3_3_3_3_3_3_3_3_3_3_3_3 |
| 2 | multiple_1_0_0_0_0_0_0_0_0_0_0_0_0_0_0_0_0 |
| 2 | multiple_1_1_1_1_1_1_1_1_1_1_1_1_1_1_1_1_1 |
| 2 | multiple_1_2_2_2_2_2_2_2_2_2_2_2_2_2_2_2_2 |
| 2 | multiple_1_3_3_3_3_3_3_3_3_3_3_3_3_3_3_3_3 |
| 3 | multiple_1_0_0_0_0_0_0_0_0_0_0_0_0_0_0_0_0 |
| 3 | multiple_1_1_1_1_1_1_1_1_1_1_1_1_1_1_1_1_1 |
| 3 | multiple_1_0_0_0_0_0_0_0_0_0_0_0_0_0_0_0_0 |
+------+-----------------------------------------------+
在sqlfiddle中测试了我的解决方案。我不得不删除order by子句,否则查询产生的结果符合问题中陈述的要求。有关详细信息,请参阅sqlfiddle。
更新问题中的结果可能是多次循环运行查询的结果。简单来说:你只是将查询粘贴到你的代码中,并且没有删除循环,即使我指出,这可能是你收到的结果的原因。