In my SQL class, I'm working with a table that is all VARCHAR. I'm trying to convert each column to a more correct data type.
For example. I have a column called Item_Cost that has a value like:
1.25000000000000000000
I tried to run this query:
ALTER TABLE <table>
ALTER COLUMN Item_Cost DECIMAL
This query does run successfully, but it turns it into 1 instead of 1.25.
How do I prevent the rounding?
Check out the documentation for the data type decimal. The type is defined by optional parameters p (precision) and s (scale). The latter determines the numbers to the right of the decimal point.
Extract from the documentation (I highlighted the important bit in bold):
s (scale)
The number of decimal digits that are stored to the right of the decimal point. This number is subtracted from p to determine the maximum number of digits to the left of the decimal point. Scale must be a value from 0 through p, and can only be specified if precision is specified. The default scale is 0 and so 0 <= s <= p. Maximum storage sizes vary, based on the precision.
Defining a suitable precision and scale fixes your issue.
Sample data
create table MyData
(
Item_Cost nvarchar(100)
);
insert into MyData (Item_Cost) values ('1.25000000000000000000');
Solution
ALTER TABLE MyData Alter Column Item_Cost DECIMAL(10, 3);
Result
Item_Cost
---------
1.250
moneydata type, and it would take care of the trailing zeroes and do no rounding.