Numeric, Float, or Decimal in SQL Server: Which Data Type Should I Choose?

SQL Server Numerical Data Types: Numeric, Float, and Decimal

Choosing the correct data type for numerical values in SQL Server is vital, especially when dealing with financial data. This guide clarifies the differences between numeric, float, and decimal data types.

Exact vs. Approximate Data Types

SQL Server offers two main categories of numerical data types:

• Exact: These types provide precise representation of numbers. Results are consistent across different hardware and regardless of number size. decimal and numeric are examples.

• Approximate: These types store approximate numerical values. They generally require less storage and can offer faster processing. float and real fall into this category.

Optimal Data Type Selection

For financial applications demanding absolute accuracy, decimal is the recommended choice. Its advantages include:

• High Precision: Supports up to 38 digits, ensuring precise storage of monetary amounts.
• Reduced Rounding Errors: Minimizes inaccuracies inherent in approximate data types.
• Accurate Computations: Improves the reliability of calculations involving rounding and comparisons.

Data Type Selection Guidelines

Follow these guidelines when choosing a numerical data type:

• Use decimal when precision is paramount and exact numerical behavior is required.
• Consider float only when the precision offered by decimal is insufficient.
• Avoid float or real in comparisons or conditions where precision is critical.

Data Type Comparison

Data Type

Precision

Storage Size

Approximate?

Data Type	Precision	Storage Size	Approximate?
decimal	Up to 38 digits	5-17 bytes	No
numeric	Up to 38 digits	5-17 bytes	No
float	24 bits (real) / 53 bits	4 bytes (real) / 8 bytes	Yes
real	24 bits	4 bytes	Yes

Up to 38 digits

5-17 bytes

No

Up to 38 digits

5-17 bytes

No

24 bits (real) / 53 bits

4 bytes (real) / 8 bytes

Yes

24 bits

4 bytes

Yes

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