mysql_fetch_array / mysqli_fetch_array - difference in behaviour on first call (php)

Question

I'm just (very belatedly I know) updating some of my code from mysql to mysqli and I've noticed what seems to be a change in behaviour in the fetch_array function.

There was no intention to obfuscate by truncating the code in the original question, but here if it helps is a fuller run down of the actual code.

USING : MYSQL

THIS STEPS THROUGH EACH QUALIFY RECORD IN THE TABLE FROM FIRST TO LAST

$con_head = mysql_connect($domain,$head_dbname,$head_dbpassword);
if (!$con_head)
  {
  die('Could not connect: ' . mysql_error());
  }
mysql_select_db($head_dbname, $con_head);


$src_sql = "Select * from SEQUENCES where SEQUENCE_TYPE = 'N' and REVIEWED ='N' order by SEQ_START";
$src_tb = mysql_query($src_sql, $con_head);

while ($src_rec = mysql_fetch_array($src_tb))
{
    ..... statements here have no relevance to the problem

}

USING MYSQLI

**THIS IMMEDIATELY SKIPS THE WHILE CLAUSE **

IF THE ROW IMMEDIATELY ABOVE WHILE IS UNCOMMENTED - THIS PROCEEDS BUT STARTING FROM THE SECOND RECORD.

$con_head = mysqli_connect("$domain,$head_dbname,$head_dbpassword,$head_dbname); // database name and user name are the same
if (!$con_head)
  {
  die('Could not connect: ' . mysqli_error());
  }
    $src_sql = "Select * from SEQUENCES where SEQUENCE_TYPE = 'N' and REVIEWED ='N' order by SEQ_START ";
$src_tb = mysqli_query($con_head, $src_sql);
//  $src_rec = mysqli_fetch_array($src_tb,MYSQLI_BOTH);
while ($src_rec = mysqli_fetch_array($src_tb,MYSQLI_BOTH))
{
    ..... statements here have no relevance to the problem

}

This works fine under mysql , but the equivalent under mysqli immediately fails the "while" test.

I've checked that otherwise the code is okay, by inserting an additional mysqli_fetch_array before commencing the loop, this works fine - although starts the processing therefore from the SECOND record.

Clearly I can rewrite my code to loop in a different way (eg having $record = mysqli_fetch_array BEFORE THE loop, having the loop testing $record and then an additional $record = mysqli_fetch_array before the end curly brace in the while loop) but I'm anxious to understand the difference in behaviour so that I don't run into any other pitfalls.

Can anyone explain?

you'll need to post what you used exactly with the `mysqli_` function. and this is wrong `mysql_query($con,$sql)` — Funk Forty Niner, Jan 15 '17 at 13:47
"the equivalent under mysqli" — What equivalent? Show us a [mcve] that demonstrates the problem, not some code which you know does not. — Quentin, Jan 15 '17 at 13:53
Ok, apologies - I didn't intend to leave anything out. I've update the above with the exact code that is demonstrating the different behaviours. — Jason Ders, Jan 15 '17 at 15:49
also, you should explain what does "immediately fails" and also prove that this "immediate fail" is not caused by "statements that have no relevance" — Your Common Sense, Jan 15 '17 at 15:50

score 2 · Answer 1 · answered Jan 15 '17 at 13:50

2

There is no difference.

Both function behave equally in every possible way.

Whatever difference you may notice is caused by your own mistake of some sort.

answered Jan 15 '17 at 13:50

Your Common Sense

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mysql_fetch_array / mysqli_fetch_array - difference in behaviour on first call (php)

1 Answers1