How can a query multiply 2 cell for each row MySQL

问题:

I want to multiply 2 cells for each row and put the value of that in the last column called Total. Can this be done by a normal query?

Example:

Pieces | Price | Total
6      |   4   |  null // should be 24
2      |  10   |  null // should be 10

回答1:

Use this:

SELECT 
    Pieces, Price, 
    Pieces * Price as 'Total' 
FROM myTable

回答2:

You can do it with:

UPDATE mytable SET Total = Pieces * Price;

回答3:

I'm assuming this should work. This will actually put it in the column in your database

UPDATE yourTable yt SET yt.Total = (yt.Pieces * yt.Price)

If you want to retrieve the 2 values from the database and put your multiplication in the third column of the result only, then

SELECT yt.Pieces, yt.Price, (yt.Pieces * yt.Price) as 'Total' FROM yourTable yt

will be your friend

回答4:

this was my solution:

i was looking for how to display the result not to calculate...

so. in this case. there is no column TOTAL in the database, but there is a total on the webpage...

 <td><?php echo $row['amount1'] * $row['amount2'] ?></td>

also this was needed first...

<?php 
   $conn=mysql_connect('localhost','testbla','adminbla');
mysql_select_db("testa",$conn);

$query1 = "select * from info2";
$get=mysql_query($query1);
while($row=mysql_fetch_array($get)){
   ?>