Oracle 参数 NLS_NUMERIC_CHARACTERS 官方解释，作用，如何配置最优化建议
本站中文解释
NLS_NUMERIC_CHARACTERS参数是控制数值显示字符，用于指定数值显示格式，即指明使用空格，逗号，句号等字符作为分隔符。
设置正确的NLS_NUMERIC_CHARACTERS参数可以让数值显示准确无误，为了避免在数据库中存在精度问题，强烈建议在建表时指定数值字段的长度和精度。
NLS_NUMERIC_CHARACTERS参数的正确设置主要依赖于数据库语言和字符集的不同，因此可以依据自己数据库的实际状况选择不同的参数设置，一般情况下，使用ALTER SESSION来设置NLS_NUMERIC_CHARACTERS：
ALTER SESSION SET NLS_NUMERIC_CHARACTERS = “., “;
在此设置中，逗号作为小数点，句号作为分组符号。
官方英文解释
NLS_NUMERIC_CHARACTERS specifies the characters to use as the group separator and decimal character.
| Property | Description |
|---|---|
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Parameter type |
String |
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Syntax |
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Default value |
Derived from |
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Modifiable |
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Modifiable in a PDB |
Yes |
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Basic |
No |
NLS_NUMERIC_CHARACTERS overrides those characters defined implicitly by NLS_TERRITORY. The group separator separates integer groups (that is, thousands, millions, billions, and so on). The decimal separates the integer portion of a number from the decimal portion.
You can specify any character as the decimal or group separator. The two characters specified must be single-byte and must be different from each other. The characters cannot be any numeric character or any of the following characters: plus (+), minus sign (-), less than sign (<), greater than sign (>). Either character can be a space.
For example, if you want to specify a comma as the decimal character and a space as the group separator, you would set this parameter as follows:
NLS_NUMERIC_CHARACTERS = ", "
Note:
The value of this initialization parameter NLS_NUMERIC_CHARACTERS is used to initialize the session value of this parameter, which is the actual value referenced by the SQL query processing. This initial value is overridden by a client-side value if the client uses the Oracle JDBC driver or if the client is OCI-based and the NLS_LANG client setting (environment variable) is defined. The initialization parameter value is, therefore, usually ignored.
See Also:
Oracle Database
Globalization Support Guide for more information about this parameter
