SELECT MAX(...在 PHP/MYSQL 中不返回任何内容
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SELECT MAX(... not returning anything in PHP/MYSQL
提问by Samik Sengupta
This is the table structure-
这是表结构-
Table: test
+------+---------+
| PAGE | CONTENT |
+------+---------+
| 1 | ABC |
+------+---------+
| 2 | DEF |
+------+---------+
| 3 | GHI |
+------+---------+
PAGEis a Primary with datatype INT(11). It does not auto-increment. CONTENT is of the datatype TEXT.
PAGE是一个具有数据类型的 Primary INT(11)。它不会自动递增。CONTENT 属于数据类型TEXT。
In PHP I do-
在 PHP 我做 -
$result = mysql_query(SELECT MAX(PAGE) FROM test);
$row = mysql_fetch_array($result);
echo $row["PAGE"];
No output. At all. If I do something like echo "Value : ".$row["PAGE"];all I see is Value :
没有输出。在所有。如果我做的事情就像echo "Value : ".$row["PAGE"];我看到的那样Value :
The query SELECT * FROM testworks just fine though. Am I wrong somewhere using the MAX()syntax?
查询SELECT * FROM test工作得很好。我在某处使用MAX()语法错了吗？
I want it to return the maximum value of PAGEas of yet.
我希望它返回PAGE迄今为止的最大值。
回答by FluffyHyman
This should be the code.
这应该是代码。
$result = mysql_query("SELECT MAX(PAGE) AS max_page FROM test");
$row = mysql_fetch_array($result);
echo $row["max_page"];
回答by paxdiablo
Shouldn't you have quotes around that query in mysql_query? I have no idea what PHP will do with such a syntactically inadequate statement, I would have thought it would have given you an error.
你不应该在该查询周围加上引号mysql_query吗？我不知道 PHP 会用这样一个语法不足的语句做什么，我原以为它会给你一个错误。
In any case, an aggregate function may have a different column name than the column used for it (from memory, DB2 gives it a similar name to the function, like max_page_or something). You may want to ensure it has the correct column name by forcing the name with something like:
在任何情况下，聚合函数的列名可能与用于它的列不同（从内存中，DB2 给它一个与函数相似的名称，例如max_page_或其他）。您可能希望通过强制使用以下名称来确保它具有正确的列名称：
$result = mysql_query("SELECT MAX(PAGE) AS MAXPAGE FROM TEST");
$row = mysql_fetch_array($result);
echo $row["MAXPAGE"];
回答by Vijai Sebastian
Try below code
试试下面的代码
$result = mysqli_query($con,"SELECT max(page2_content_id) AS max_page from page2_content_data");
$row = mysqli_fetch_array($result);
echo $row["max_page"];
Where $con=new mysqli($server,$user,$password,$db_name);and page2_content_datais my table,and page2_content_idis the column name
凡$con=new mysqli($server,$user,$password,$db_name);与page2_content_data是我的表，page2_content_id是列名
回答by Bruce Ballad
I used something like this in my code;
我在我的代码中使用了这样的东西；
$maxscore_query = mysql_query("SELECT MAX(`score`) FROM `allscores` WHERE`level`='$levelcode'");
echo mysql_result($maxscore_query, 0);
The difference here is the use of WHERE for selecting a group.
这里的区别在于使用 WHERE 来选择一个组。
And mysql_result($maxscore_query, 0);is easier to manage for me.
而且mysql_result($maxscore_query, 0);对我来说更容易管理。
回答by im-sunil
$connect = mysqli_connect("localhost", "root", "", "carBid") or die("not connected");
//connection to database
$sql2 = "SELECT max(mybid) FROM `bid`";
//simle select statement with max function
$result_set2 = mysqli_query($connect,$sql2);
//query a result fetch
if ($result_set2) {
$rowB = mysqli_fetch_array($result_set2);
//feching a result in array format
echo $rowB['max(mybid)'];
//accessing array by name of column with max() function of mysql
} else {
echo 'No Current Bid';
}
mysqli_close($connect);
