Question: What is the Difference Among DECIMAL, FLOAT and NUMERIC Datatype?
The basic difference between Decimal and Numeric :
They are the exact same. Same thing, different name.
The basic difference between Decimal/Numeric and Float :
Float is Approximate-number data type, which means that not all values in the data type range can be represented exactly.
Decimal/Numeric is a Fixed-Precision data type, which means that all the values in the data type can be represented exactly with precision and scale.
Converting from Decimal or Numeric to float can cause some loss of precision. For the Decimal or Numeric data types, SQL Server considers each specific combination of precision and scale as a different data type. DECIMAL(2,2) and DECIMAL(2,4) are different data types. This means that 11.22 and 11.2222 are different types, though this is not the case for float. For FLOAT(6) 11.22 and 11.2222 are same data types.
Well, this is a very simple interview question and I honestly expect everyone to know this as this is basic of computer science than a SQL Server specific question. With that said, I also have the opinion that this kind of question does not judge people’s SQL skills.
Reference: Pinal Dave (https://blog.sqlauthority.com)