Am getting errors from my db in android app

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Hello Guys i want to select values and show in textbox but i am getting on my edittext on button click
here is the error

<br /> Warning:  mysqli_num_rows() expects parameter 1 to be mysqli_result, boolean given in /h7/ae/public_html/fashion360/Com.php on line 11<br /> []

please help me please tell me whats the matter and how can i resolved this error
thanks

What I have tried:

<?php
include 'Db.php';
$con=mysqli_connect($HostName,$HostUser,$HostPass,$DatabaseName)or die("Cannot Connect");
mysqli_select_db($con,$DatabaseName)or die("Cannot select db");
mysqli_set_charset($con,'utf8');
$sql = "SELECT TOP 1 complainno FROM complain";
$result  =mysqli_query($con,$sql);
$json = array();
if(mysqli_num_rows($result)){
while ($row=mysqli_fetch_assoc($result)){
$json['complainno'][]=$row;
}
}
mysqli_close($con);
echo json_encode($json);
?>

Posted 31-Jan-18 1:28am

Member 9983063

Updated 31-Jan-18 2:35am

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David Crow 31-Jan-18 9:21am

The error seems to be strictly PHP related. You might consider removing the Android and Java tags.

1 solution

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Jochen Arndt · Accepted Answer · 2018-01-31T02:35:00

Solution 1

Your PHP: mysqli::query - Manual[^] call failed:

Quote:

Return Values

Returns FALSE on failure. For successful SELECT, SHOW, DESCRIBE or EXPLAIN queries mysqli_query() will return a mysqli_result object. For other successful queries mysqli_query() will return TRUE.

It is always a good idea to check return values and display error messages upon errors to know what went wrong:

PHP

if ($result = mysqli_query($con,$sql)) {
    // Query was successful: Move on
}
else {
    printf("Error: %s\n", mysqli_error($con));
}

In your case it is probably a syntax error in the query string. As far as I know, MySQL does not know the TOP command. You have to use LIMIT instead:

PHP

$sql = "SELECT complainno FROM complain LIMIT 1";

Posted 31-Jan-18 2:35am

Jochen Arndt

Comments

Member 9983063 31-Jan-18 14:37pm

Hello thanks for your help am trying your query now and am getting error also
i am using now
<?php
include 'DatabaseConfig.php';
$con=mysqli_connect($HostName,$HostUser,$HostPass,$DatabaseName)or die("Cannot Connect");
mysqli_select_db($con,$DatabaseName)or die("Cannot select db");
mysqli_set_charset($con,'utf8');
$sql = "SELECT complainno FROM complain LIMIT 1";
$result =mysqli_query($con,$sql);
$json = array();
if(mysqli_num_rows($result)){
while ($row=mysqli_fetch_assoc($result)){
$json['complainno'][]=$row;
}
}
mysqli_close($con);
echo json_encode($json);
?>
please see the error in this screen shot
https://imgur.com/a/QlhoV

Jochen Arndt 1-Feb-18 2:59am

The mysqli_query() call is still failing. Please use also the error reporting code from my solution. It gives you more information.

Note also that using mysqli_num_rows() makes no sense when the query is limited to return only one row.

Member 9983063 1-Feb-18 3:03am

so how can i resolve it

Jochen Arndt 1-Feb-18 3:16am

You have to pass a valid SQL command as query string.

But I don't have your database and can't therefore reproduce it. The first step is - as already suggested - getting the error message from the database interface by calling mysqli_error($con).

Member 9983063 1-Feb-18 4:08am

well sir my errors are resolved thanks for your help and sir just one thing when i select value with order by table name Desc so it's select asc values but i want Desc values

Jochen Arndt 1-Feb-18 4:15am

ORDER BY requires column names, not table names.

Member 9983063 1-Feb-18 4:17am

yea sorry i was mean select value with order by column name Desc

Jochen Arndt 1-Feb-18 5:37am

It should work. But I can't test or verify it as already mentioned.
Print the results to check it (using a JSON table and showing that might be affected by it#s own sorting).

Member 9983063 1-Feb-18 5:40am

i have checked everything but i dont understand how to resolved it