datoshway Posted February 5, 2011 Share Posted February 5, 2011 I am building a small cart and need a way subtract a numeral from one table from another table holding the order items and quantity. Need some help devising a query to subtract. Below is what I have, it's not right but just put it in so you can see basically what I am working with. I'm nooby please help. Assuming I need some kind of join statement and some help with this below? $qty=$intQuantity; mysql_query('UPDATE tblItems SET intQuantity-intQuantity WHERE intID = %d) or die(mysql_error()); Database structors Table 1(tblItems) intID | intQuantity 1 | 3 Table 2(tblOrderItems) intID | intQuantity | intItemID 200 2 1 Quote Link to comment Share on other sites More sharing options...
datoshway Posted February 5, 2011 Author Share Posted February 5, 2011 Here is a little more of a developed idea of what i'm looking for then my last attempt $strQuery = sprintf( "UPDATE tblItems SET intQuantity = intQuantity - (SELECT intQuantity FROM tblOrderItems WHERE intItemID = %d) WHERE intItemID = intID)", Quote Link to comment Share on other sites More sharing options...
fenway Posted February 13, 2011 Share Posted February 13, 2011 Why the subquery -- just substract. Quote Link to comment Share on other sites More sharing options...
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