Regular Expression Operator Multilingual Enhancements
When applied to multilingual data, Oracle’s implementation of the POSIX operators extends beyond the matching capabilities specified in the POSIX standard. Table D-2 shows the relationship of the operators in the context of the POSIX standard.
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The first column lists the supported operators.
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The second and third columns indicate whether the POSIX standard (Basic Regular Expression—BRE and Extended Regular Expression—ERE, respectively) defines the operator
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The fourth column indicates whether Oracle’s implementation extends the operator’s semantics for handling multilingual data.
Oracle lets you enter multibyte characters directly, if you have a direct input method, or you can use functions to compose the multibyte characters. You cannot use the Unicode hexadecimal encoding value of the form ‘\xxxx’. Oracle evaluates the characters based on the byte values used to encode the character, not the graphical representation of the character. All accented characters are considered word characters.
Table 2 POSIX and Multilingual Operator Relationships
| Operator | POSIX BRE syntax | POSIX ERE Syntax | Multilingual Enhancement |
|---|---|---|---|
| \ | Yes | Yes | - |
| * | Yes | Yes | - |
| + | – | Yes | - |
| ? | - | Yes | - |
| | | - | Yes | - |
| ^ | Yes | Yes | Yes |
| $ | Yes | Yes | Yes |
| . | Yes | Yes | Yes |
| [ ] | Yes | Yes | Yes |
| ( ) | Yes | Yes | - |
| {m} | Yes | Yes | - |
| {m,} | Yes | Yes | - |
| {m,n} | Yes | Yes | - |
| \n | Yes | Yes | Yes |
| [..] | Yes | Yes | Yes |
| [::] | Yes | Yes | Yes |
| [==] | Yes | Yes | Yes |