Difference between numeric, float and decimal in S

Question

I searched in Google and also visited decimal and numeric and SQL Server Helper to glean the difference between numeric, float and decimal datatypes and also to find out which one should be used in which situation.

For any kind of financial transaction (e.g. for salary field), which one is prefered and why?

Answer 1

They Differ in Data Type Precedence

Decimal and Numeric are the same functionally but there is still data type precedence, which can be crucial in some cases.

SELECT SQL_VARIANT_PROPERTY(CAST(1 AS NUMERIC) + CAST(1 AS DECIMAL),'basetype')

The resulting data type is numeric because it takes data type precedence.

Exhaustive list of data types by precedence:

Reference link

Answer 2

Float is Approximate-number data type, which means that not all values in the data type range can be represented exactly.

Decimal/Numeric is Fixed-Precision data type, which means that all the values in the data type range can be represented exactly with precision and scale. You can use decimal for money saving.

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.

You can also use money data type for saving money. This is native data type with 4 digit precision for money. Most experts prefers this data type for saving money.

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