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    <p>If you only store id and name for color it could very well be a php function, so you don't need a color table:</p> <pre><code>&lt;?PHP function color($color) { $colors['red']=1; $colors['blue']=2; $colors['green']=3; return $colors[$color]; } //example of usage $sql ="... where `color`=".color($_POST['color'])." "; ?&gt; </code></pre> <p>Also since size is a small value (is not a big text for example) then you don't need a size table at all. All you need is a product and a quantity (better rename it to product_info) table:</p> <pre><code>mysql_query(" CREATE TABLE `Product` ( `product_id` INT UNSIGNED NOT NULL AUTO_INCREMENT, `product_name` varchar(30) NOT NULL , unique(`product_name`), PRIMARY KEY (`product_id`) ) ENGINE=InnoDB ROW_FORMAT=COMPACT;") or die(mysql_error()); mysql_query(" CREATE TABLE `Product_Info` ( `product_id` INT UNSIGNED NOT NULL , `color_code` char(3) NOT NULL , `prod_col_size` varchar(15) NOT NULL , `quantity` mediumint UNSIGNED NOT NULL , PRIMARY KEY (`product_id`,color_code,prod_col_size), CONSTRAINT `prod_id_FK` FOREIGN KEY (`product_id`) REFERENCES `Product` (`product_id`) ON DELETE CASCADE ) ENGINE=InnoDB ROW_FORMAT=COMPACT;") or die(mysql_error()); </code></pre> <p>This is not perfect normalization but you already choosed this way. The queries will be very easy this way. To bother with long joins in a well normalized schema makes sense. To bother for no reason at all!? You only need to make a join in two tables in case you need some filed from the product table.</p> <pre><code> /*Find how many red items has a specific product*/ select sum(`Product_Info`.`quantity`) from `Product_Info` where `color_code`='124' and `product_id`='3'; </code></pre>
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