Im trying to figure out how to handle this is no results are returned, how would I code that?
while($row = mysql_fetch_array($Result))
So like if there a results: print them out
else: show a link
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6 Answers
https://www.php.net/manual/en/function.mysql-num-rows.php
if(mysql_num_rows($result) > 0) {
while($row = mysql_fetch_array($result)) { ... }
} else {
// show link
}
Comments
You can use mysql_num_rows() to tell you how many results are found. Using that with a simple if-statement, and you can determine what action to take.
if (mysql_num_rows($result) > 0) {
// do while loop
} else {
// show link
}
3 Comments
alex
Just wondering - will the resulting value from that function always be falsy if it fails or no results? Could omit the greater than 0 if so (I always have, but have never thought too much in depth about possible return values) +1
Sampson
"Return Values: The number of rows in a result set on success or FALSE on failure." It seems that this may return
0 if indeed there are zero results, but false if the function fails.
jrutter
Excellent. Worked perfectly, better than how I had found.
Others suggest using mysql_num_rows() but you should be aware that that function works only if you use a buffered query. If you query using mysql_unbuffered_query(), the number of rows in the result is not available.
I would use a simple flag variable:
$found_row = false;
while ($row = mysql_fetch_array($result)) {
$found_row = true;
. . .
}
if ($found_row == false) {
// show link
}
It may seem redundant to set $found_row to true repeatedly, but assigning a literal value to a variable ought to be an insignificant expense in any language. Certainly it is small compared to fetching and processing an SQL query result.
2 Comments
mpen
Languages should have a construct to avoid this problem, since it's so common. Something like
while($cond){$action}else{$code}.
Bill Karwin
@Mark: Python has a while/else construct.
Use even shorter syntax without insignificant mysql_num_rows to save processor time:
if($result) {
// return db results
} else {
// no result
}
Comments
I might have figured it out:
if (!($row = mysql_fetch_array($descResult)))
{
echo "<tr><td>Add Link</td></tr>";
}
Comments
This can be done without mysql_num_rows() or an additional (flag) variable
if ( false===($row=mysql_fetch_array($result, MYSQL_ASSOC)) ) {
echo 'no rows in result set';
}
else {
do {
echo $row['X'];
} while ( false===($row=mysql_fetch_array($result, MYSQL_ASSOC)) );
}
but it duplicates the actual fetch command (one in the if-statement and one in the while-clause).
