使用计算在查询中返回 2 个额外的列

Question

What I want to do is probably very simple, but I have a table:

|---------------------|------------------|
|          ID         |       price      |
|---------------------|------------------|
|          1          |         30       |
|---------------------|------------------|

Which query I am using in this procedure:

PROCEDURE `get_info`(IN itemID VARCHAR(255), IN itemQuantity VARCHAR(255)) 
BEGIN
SELECT * from table where ID = itemID;
END

Now I would like the query to return 2 extra columns, with "quantity", which is procedures input "itemQuantity" and the extra column "totalPrice" which is itemQuantity*price.

So the table looks like this:

|---------------------|------------------|----------------------|------------------|
|          ID         |       price      |       quantity       |     totalPrice   |
|---------------------|------------------|----------------------|------------------|
|          1          |         30       |          2           |        60        |
|---------------------|------------------|----------------------|------------------|

I can return everything separately, but how do I combine it into one query result?

Answer 1

Is this what you want?

PROCEDURE `get_info`(
    IN in_itemID VARCHAR(255),
    IN in_itemQuantity VARCHAR(255)) 
BEGIN
    SELECT t.*, in_itemQuantity as itemQuantity, in_itemQuantity * t.price as totalprice
    FROM table t
    WHERE t.ID = in_itemID;
END;

Notice that I changed the names of the parameters, by prefixing them with in_ . This significantly reduces the chance that the parameter conflicts with an existing column name.