Help with PHP, MYSQL query to get MAX ID of a Table

I need a little help figuring out how to get the max id of a table. My Table has Column ID set to AUTO_INCREMENT and is the Primary Keyname. I need to get the MAX ID and assign variables to some of the columns on that row.


The following successfully give me the value of "Column3" & "Column4" Where ID is 10.
$con=mysqli_connect("host","user","pass","MY_DB");
$result = mysqli_query($con,"SELECT * FROM Table WHERE ID='10'");
$row1 = mysqli_fetch_array($result);
$C3 = $row1['Column3'];
$C4 = $row1['Column4'];
echo $C3;
echo $C4;

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But when I try to select the MAX ID my page is blank. I have tried several examples I found online and nothing seems to work.
$con=mysqli_connect("host","user","pass","MY_DB");
$result = mysqli_query($con,"SELECT * FROM Table WHERE ID='(SELECT MAX(ID) FROM Table)'";
$row1 = mysqli_fetch_array($result);
$C3 = $row1['Column3'];
$C4 = $row1['Column4'];
echo $C3;
echo $C4;


$con=mysqli_connect("host","user","pass","MY_DB");
$result = mysqli_query($con,"SELECT * FROM Table WHERE ID=MAX(ID)";
$row1 = mysqli_fetch_array($result);
$C3 = $row1['Column3'];
$C4 = $row1['Column4'];
echo $C3;
echo $C4;

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Can someone show me the correct way to get the Max ID?
LVL 3
mlsbravesAsked:
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Richard DavisSenior Web DeveloperCommented:
Have you considered this route?

SELECT row FROM table ORDER BY id DESC LIMIT 1;

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1
Haris DulicCommented:
Can you try like this :

$con=mysqli_connect("host","user","pass","MY_DB");
$result = mysqli_query($con,"SELECT * FROM Table WHERE ID=(SELECT MAX(ID) FROM Table)";
$row1 = mysqli_fetch_array($result);
$C3 = $row1['Column3'];
$C4 = $row1['Column4'];
echo $C3;
echo $C4;

Open in new window

0
mlsbravesAuthor Commented:
Both give me a blank page.

$con=mysqli_connect("host","user","pass","MY_DB");
$result = mysqli_query($con,"SELECT row FROM table ORDER BY id DESC LIMIT 1");
$row1 = mysqli_fetch_array($result);
$C3 = $row1['Column3'];
$C4 = $row1['Column4'];
echo $C3;
echo $C4;

Open in new window


$con=mysqli_connect("host","user","pass","MY_DB");
$result = mysqli_query($con,"SELECT * FROM Table WHERE ID=(SELECT MAX(ID) FROM Table)";
$row1 = mysqli_fetch_array($result);
$C3 = $row1['Column3'];
$C4 = $row1['Column4'];
echo $C3;
echo $C4;

Open in new window

0
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Haris DulicCommented:
Hi,

can you check like this and then see if there is anything in that last row?

$con=mysqli_connect("host","user","pass","MY_DB");
$result = mysqli_query($con,"SELECT * FROM Table WHERE ID=(SELECT MAX(ID) FROM Table)";
$row1 = mysqli_fetch_array($result);
$C3 = $row1['Column3'];
$C4 = $row1['Column4'];
$C5 = $row1['ID'];
echo $C3;
echo $C4;
echo $C5;

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0
Richard DavisSenior Web DeveloperCommented:
Sounds like you have something wrong with your data. Perhaps an empty row?
Have you tried my suggestion I originally posted also yet?
0
Brian TaoSenior Business Solutions ConsultantCommented:
samo4fun's code should work, except that it's missing the closing ")" in line 2.  So, by copying and modifying his code:
$con=mysqli_connect("host","user","pass","MY_DB");
$result = mysqli_query($con,"SELECT * FROM Table WHERE ID=(SELECT MAX(ID) FROM Table)");
$row1 = mysqli_fetch_array($result);
$C3 = $row1['Column3'];
$C4 = $row1['Column4'];
echo $C3;
echo $C4;

Open in new window


Please try.
0
mlsbravesAuthor Commented:
Ok just tried this on a new DB I created and I'm getting the same result and the row is not empty.

DB Name: TEST_DB
Table: my_data

DB-Structure
DB-Data
When I use the following I get the correct results for the variables:
<?php
$con=mysqli_connect("host","user","password","TEST_DB");
$result = mysqli_query($con,"SELECT * FROM my_data WHERE ID='5'");
$row1 = mysqli_fetch_array($result);
$C3 = $row1['Status'];
$C4 = $row1['Money'];
$C5 = $row1['ID'];
echo $C3;
echo $C4;
echo $C5;
?>

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But the other two codes give me a black page:
<?php
$con=mysqli_connect("host","user","password","TEST_DB");
$result = mysqli_query($con,"SELECT row FROM my_data ORDER BY id DESC LIMIT 1");
$row1 = mysqli_fetch_array($result);
$C3 = $row1['Status'];
$C4 = $row1['Money'];
$C5 = $row1['ID'];
echo $C3;
echo $C4;
echo $C5;
?>

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<?php
$con=mysqli_connect("host","user","password","TEST_DB");
$result = mysqli_query($con,"SELECT * FROM my_data WHERE ID=(SELECT MAX(ID) FROM my_data)";
$row1 = mysqli_fetch_array($result);
$C3 = $row1['Status'];
$C4 = $row1['Money'];
$C5 = $row1['ID'];
echo $C3;
echo $C4;
echo $C5;
?>

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0
Haris DulicCommented:
can you do this sql directly in the database and post the result .. if any
0
Brian TaoSenior Business Solutions ConsultantCommented:
Did you read my comment at http://www.experts-exchange.com/Programming/Languages/Scripting/PHP/Q_28536952.html#a40379173 ?

The problem in adrian_brooks's comment (your first try) was that you don't have a "row" column in the table and he was just giving you an example on SQL but you directly copied and pasted it.

The problem in samo4fun's comment (your second try) was that you were missing the end parentheses ")" in the line
$result = mysqli_query($con,"SELECT * FROM my_data WHERE ID=(SELECT MAX(ID) FROM my_data)";

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and it should be
$result = mysqli_query($con,"SELECT * FROM my_data WHERE ID=(SELECT MAX(ID) FROM my_data)");

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Good luck!
0

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Haris DulicCommented:
Nice catch ;) Missed that parentheses twice...:)
0
mlsbravesAuthor Commented:
Thanks for all the help. Both Codes work after reading taoyipai post. I was thinking row was apart of the statement for some reason lol. Once I put the code in NetBeans it quickly showed me the syntax error as well.
0
Richard DavisSenior Web DeveloperCommented:
I posted what I did because I figured I didn't need to explain that it was meant to be pseudo code and that the author needed to modify the query to fit his/her needs. Lesson learned here, "never assuming anything".
0
Ray PaseurCommented:
The "blank page" is a symptom of a misconfigured PHP installation.  When you're in a deployed environment it might make sense, but it makes no sense at all for a development environment.  You want to be able to see what you're doing.  Look into error_reporting(), log_errors() and display_errors().  These are all documented at http://php.net and once you have the right settings you will be able to catch and correct errors much more easily!
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