problem updating database

I don't understand where I'm going wrong in this:

PHP Code:

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for($j=1; $j<=18; $j++){
    $sql = "UPDATE boti_pages SET chapter = '".$chapTitles[$j][0]."' WHERE page_num >= '".$chapTitles[0][$j]."' AND page_num < '".$chapTitles[0][$j+1]."'";
echo $sql."<br />";
} 


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PHP Code:

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$chapTitles[1][0] = "Introduction"; 
$chapTitles[0][1] =  "1";

$chapTitles[2][0] = "chapter 1";
$chapTitles[0][2] =  "5";

$chapTitles[3][0] = "chapter 2"; 
$chapTitles[0][3] =  "17";

$chapTitles[4][0] = "chapter 3";
$chapTitles[0][4] =  "18";

$chapTitles[5][0] = "chapter 4";
$chapTitles[0][5] =  "27";

$chapTitles[6][0] = "chapter 5";
$chapTitles[0][6] =  "48"; 


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Echo-ing the SQL I get:

Quote:

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UPDATE boti_pages SET chapter = 'Introduction' WHERE page_num >= '1' AND page_num < '5'
UPDATE boti_pages SET chapter = 'chapter 1' WHERE page_num >= '5' AND page_num < '17'
UPDATE boti_pages SET chapter = 'chapter 2' WHERE page_num >= '17' AND page_num < '18'
UPDATE boti_pages SET chapter = 'chapter 3' WHERE page_num >= '18' AND page_num < '27'
UPDATE boti_pages SET chapter = 'chapter 4' WHERE page_num >= '27' AND page_num < '48'
UPDATE boti_pages SET chapter = 'chapter 5' WHERE page_num >= '48' AND page_num < '62'

---

But there is no entry into the database in the chapter field.

You don't seem to be executing your SQL statements? :)

I forgot to include:
$result = mysql_query($sql) OR exit( 'Error: ' . mysql_error() );

You mean you forgot to include in what you posted above? Or had you forgotten in your code and now you added it and it works?