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SQL Server

SQL Server numeric, float and decimals

In general use the float or real data types only if the precision provided by decimal (up to 38 digits) is insufficient

so generally because the precision provided by decimal is [10E38 ~ 38 digits] if your number can fit in it, do not look at float.

some more Geekologie…

  • numeric = decimal (5 to 17 bytes) (Exact Numeric Data Type)
    • will map to Decimal in .NET
    • both have (18, 0) as default (precision,scale) parameters in SQL server
    • scale = maximum number of decimal digits that can be stored to the right of the decimal point.
    • kindly note that money(8 byte) and smallmoney(4 byte) are also exact and map to Decimal In .NET and have 4 decimal points(MSDN)
    • decimal and numeric (Transact-SQL) – MSDN
  • real (4 byte) (Approximate Numeric Data Type)
  • float (8 byte) (Approximate Numeric Data Type)
    • will map to Double in .NET
  • All exact numeric types always produce the same result, regardless of which kind of processor architecture is being used or the magnitude of the numbers
  • The parameter supplied to the float data type defines the number of bits that are used to store the mantissa of the floating point number.
  • Approximate Numeric Data Type usually uses less storage and have better speed (up to 20x) and you should also consider when they got converted in .NET

Exact Numeric Data Types Approximate Numeric Data Types

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About ldgaller

Accomplished Data Warehouse Architect, DBA and Software Architect with over 15 years of professional experience and demonstrated success designing and implementing solutions that improve business functionality and productivity. Highly diverse technical background with proven ability to design, develop and implement technology on an enterprise level. I approach all projects with passion, diligence, integrity, and exceptional aptitude.

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