Data type choice: float or decimal

[mbabcock]

What are the ramifications of choosing the specific data type of these two (float or decimal)? I need to store numerics with known decimal widths, and then do calculations on them later (multiplying and adding specifically) inside UDFs/stored procs.

Tia!
--Michael

 

[rac2]

See Books Online topic, data types-SQL Server, decimal.

Essentially

The decimal data type can store a maximum of 38 digits, all of which can be to the right of the decimal point. The decimal data type stores an exact representation of the number; there is no approximation of the stored value.
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The float and real data types are known as approximate data types.
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do not use these data types when exact numeric behavior is required, such as in financial applications, in operations involving rounding, or in equality checks.
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Avoid using float or real columns in WHERE clause search conditions, especially the = and <> operators. It is best to limit float and real columns to > or < comparisons.

 

[macroCharlie]

From 2000BOL: Approximate number data types for use with floating point numeric data. Floating point data is approximate; not all values in the data type range can be precisely represented.