Last updated on 2024年5月23日

What are the differences between DECIMAL and NUMERIC data types in DB2?

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DECIMAL and NUMERIC are two common data types in DB2 that can store exact numeric values with a fixed precision and scale. They are often used for monetary, scientific, or statistical calculations that require accuracy and consistency. However, there are some subtle differences between them that you should know before choosing one over the other. In this article, we will compare and contrast DECIMAL and NUMERIC data types in DB2 and explain how they affect your SQL queries and performance.

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Shashank Sahu

SQL Server || Microsoft PowerBI || Advanced Excel || Java || Python || JavaScript || Linux || Btech CSE 22 ||…

1 Precision and scale

Both DECIMAL and NUMERIC data types have two parameters: precision and scale. Precision is the maximum number of digits that can be stored, and scale is the number of digits after the decimal point. For example, DECIMAL(8,2) can store up to eight digits, with two of them being fractional. The range of values for DECIMAL and NUMERIC is the same, from -10^(precision-scale) to 10^(precision-scale)-1. However, the default values for precision and scale are different. If you do not specify them, DECIMAL defaults to (5,0), while NUMERIC defaults to (15,0).

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Shashank Sahu

SQL Server || Microsoft PowerBI || Advanced Excel || Java || Python || JavaScript || Linux || Btech CSE 22 || Ex-InfoCepts || LinkedIn Content Contributor
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DECIMAL and NUMERIC data types in SQL are nearly same. What differentiates the two is the precision and scale. Precision is higher in NUMERIC, while it is smaller in DECIMAL data type. The scale in both data types is the same. It is recommended to use DECIMAL when dealing with smaller values and to not use NUMERIC unnecessary to save memory.

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Priscillar Simon Banda (MPH, Business strategy, B.Ed)

Data Analytics| Databases | GDG Lead| Mandela Washington Fellow| AI educator | Board Member| Women Tech Makers
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I'll give you an example in a system i am working on. Choosing the appropriate DB2 data type—such as DECIMAL or NUMERIC—DECIMAL stores numbers with predetermined total digits and decimal places, ensuring accuracy for financial aid amounts or daily food rations. While NUMERIC offers greater control over internal representation, it is less flexible in terms of storage efficiency. When it comes to maximizing accuracy in financial computations or guaranteeing appropriate resource distribution, DECIMAL is the recommended option. For less sensitive numeric data, such as the number of people in a camp, NUMERIC may be appropriate if small variances in storage efficiency are acceptable.

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2 Storage and performance

Another difference between DECIMAL and NUMERIC data types is how they are stored and how they affect the performance of your SQL queries. DECIMAL data types are stored as binary-coded decimal (BCD) values, which means that each digit is encoded as a four-bit binary value. This makes DECIMAL data types more compact and efficient for arithmetic operations, as they do not require any conversion or rounding. NUMERIC data types, on the other hand, are stored as character strings, which means that each digit is encoded as an eight-bit ASCII value. This makes NUMERIC data types more flexible and compatible with other data sources, as they can handle different formats and separators. However, this also means that NUMERIC data types require more storage space and processing time, as they need to be converted to and from binary values for arithmetic operations.

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Shashank Sahu

SQL Server || Microsoft PowerBI || Advanced Excel || Java || Python || JavaScript || Linux || Btech CSE 22 || Ex-InfoCepts || LinkedIn Content Contributor
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While both data types, DECIMAL and NUMERIC are almost same, but what makes a difference is the efficiency and space. DECIMAL data types are stored as BCD, which makes this more compact and efficient as compared to NUMERIC data types.

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3 Compatibility and portability

The final difference between DECIMAL and NUMERIC data types is how they are compatible and portable across different platforms and versions of DB2. DECIMAL data types are part of the SQL standard and are supported by most relational database management systems (RDBMS). This means that you can use DECIMAL data types in your SQL queries without worrying about compatibility issues or syntax differences. NUMERIC data types, however, are specific to DB2 and are not part of the SQL standard. This means that you may encounter some challenges or limitations when using NUMERIC data types with other RDBMS or versions of DB2. For example, some RDBMS may not support NUMERIC data types at all, or may have different rules for precision and scale. Similarly, some versions of DB2 may have different maximum values for precision and scale for NUMERIC data types.

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Shashank Sahu

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The main difference between DECIMAL and NUMERIC data types is compatibility and portability. While DECIMAL data type is compatible and supported by most relational database management systems, NUMERIC data type might have compatibility issues or precision differences.

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4 Here’s what else to consider

This is a space to share examples, stories, or insights that don’t fit into any of the previous sections. What else would you like to add?

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What are the differences between DECIMAL and NUMERIC data types in DB2?

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1 Precision and scale

2 Storage and performance

3 Compatibility and portability

4 Here’s what else to consider

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