SQL Multiplication - Update Query

SQL 2008 - Simple Query logic.

In my Table :TableName, i have 3 columns [Ship Qty], Size, Qty.

Default value for Qty is NULL. I wrote an Update Query to update the column : Qty. I need to multiply [Ship Qty] * Size.

Column : Size is nvarchar. It carries two conditons

1) If the value is 60 EA or 3 ML, I need to consider only 60 or 3 or 3.5 ...

2) If the value is 60X3 ML, I need to consider 60X3 which is 180. Th开发者_如何学Cen, this multiplied value will be multiplied with [Ship Qty].

update [TableName]
set Qty = [Ship Qty] * CONVERT(INT, (Size)) * CONVERT(Float, (Size))     
           WHERE  Size > 0         
           AND Size > 0         
           AND Qty IS NULL


Ship Qty    Size             Qty
1           100 EA           100
3           60 EA            180
2           60X3ML           360

In the above table, Column : Qty is updated through SQL Query. My Query throws exception.

Bad/odd design but for what hopefully a one-off fix;

;with TEST ([Ship Qty], Size) as (
    select 1,'100 EA' union all
    select 3,'60 EA'  union all
    select 2,'60X3ML' union all
    select 2,'60X2ML' union all
    select 2,'60'     union all
    select 2,'1 X3PP'
)
select 
    [Ship Qty],
    Size,
    [Ship Qty] * (
            cast(substring(Size, 1, patindex('%[^0-9]%', Size + '/') - 1) as int)
            *
            case when charindex('X', Size, 1) > 0 then
                cast(substring(substring(Size, charindex('X', Size) + 1, len(Size)), 1, patindex('%[^0-9]%', substring(Size, charindex('X', Size) + 1, len(Size)) + '/') - 1) as int)
            else 
                1
            end
        )
from TEST

For

Ship Qty    Size    (No column name)
1           100 EA  100
3           60 EA   180
2           60X3ML  360
2           60X2ML  240
2           60      120
2           1 X3PP  6

You have several problems:

• First: It seems to me that your multiplication may return a float and yet your QTY column looks like is defined as an integer
• Second (definitely an issue): You are converting the Size column, which has strings to a float. How do you expect that to work?
• Third: Why do you have two QTY columns in your example data? Where's the Ship QTY Column you refer to?