DECIMAL values being converted to INT + 1 on its own

Question

I have a C# app where the user fills a form to store a product in a SQL Server database.

The problem is that every time a product is stored (through the user filling a form), the price (a decimal) is automatically converted to int and has 1 added to it.

I initially thought it was an issue with the app, however, the registration process is pretty simple and I didn't find any error there, so I inserted a row directly from SQL Server and the issue presented itself, so this tells me the issue is in SQL Server, not in the app .

Executing

insert into product (code, description, unit_price, stock, category_code)
values (7, 'Window Cleaner', 20.50, 20, 3)

Results into price being 21.

This is the table definition

CODE INT NOT NULL,
DESCRIPTION VARCHAR(30) NOT NULL,
UNIT_PRICE DECIMAL NOT NULL,
STOCK INT NOT NULL,
CATEGORY_CODE INT NOT NULL
CONSTRAINT PK_PRODUCT PRIMARY KEY(CODE),
CONSTRAINT FK_CATEGORY_CODE FOREIGN KEY (CATEGORY_CODE) REFERENCES Category(CODE),
CONSTRAINT PRODUCT_POSITIVE_VALUES CHECK(UNIT_PRICE > 0 AND CODE >= 0 AND STOCK >= 0)

Answer 1

You have used the following to define your column:

UNIT_PRICE DECIMAL NOT NULL

This has no precision nor scale and will therefore use the default precision (18) and scale (0). The default scale of 0 is effectively an int . So when you insert/update a value the value will get rounded to an int . To solve your problem define your column with the correct precision and scale eg

UNIT_PRICE DECIMAL(9,2) NOT NULL

Reference