Oracle Regular Expressions Pocket Reference (2024)

FAQs

What is the difference between REGEXP_LIKE and regexp_substr? ›

REGEXP_LIKE - Similar to LIKE except it uses a regular expression as the search string. REGEXP_LIKE is really an operator, not a function. REGEXP_REPLACE - Similar to REPLACE except it uses a regular expression as the search string. REGEXP_SUBSTR - Returns the string matching the regular expression.

Oracle SQL supports regular expressions with the pattern-matching condition and functions summarized in Table 11-1. Each pattern matcher searches a given string for a given pattern (described with a regular expression), and each has the pattern-matching options described in Table 11-2.

The INSTR functions search string for substring . The function returns an integer indicating the position of the character in string that is the first character of this occurrence. INSTR calculates strings using characters as defined by the input character set.

Based on the results of this JMH benchmark, string operations are faster than regex operations in Java, even if the two operations are logically the same, like String.

Syntax Alternatives: REGEXP_EXTRACT is a synonym for REGEXP_SUBSTR.

To avoid problems, do not use special characters such as ( & @ * $ | % ~ -) in object names, except for underscore (_). Also do not use Oracle SQL or PL/SQL reserved words in object names, especially the Oracle name.

REGEXP_SUBSTR extends the functionality of the SUBSTR function by letting you search a string for a regular expression pattern. It is also similar to REGEXP_INSTR , but instead of returning the position of the substring, it returns the substring itself.

REGEXP_REPLACE extends the functionality of the REPLACE function by letting you search a string for a regular expression pattern. By default, the function returns source_char with every occurrence of the regular expression pattern replaced with replace_string .

It can contain up to 512 bytes. If the datatype of pattern is different from the datatype of source_string , Oracle converts pattern to the datatype of source_string .

How do I know if RegEx is working? ›

Use test() whenever you want to know whether a pattern is found in a string. test() returns a boolean, unlike the String.prototype.search() method (which returns the index of a match, or -1 if not found). To get more information (but with slower execution), use the exec() method.

REGEXP_INSTR extends the functionality of the INSTR function by letting you search a string for a regular expression pattern. The function evaluates strings using characters as defined by the input character set.

You can find the first occurrence of a given character in a string in Python by using the `str. index()` method. This method returns the index of the first occurrence of the specified character. If the character is not found, it raises a `ValueError`.

The contains() method checks whether a string contains a sequence of characters. Returns true if the characters exist and false if not.

SELECT 1 FROM dual WHERE regexp_like('CHRIS KAIZER, APS®, CoC® Chief Advisor', '. [^[:alnum:]]|[^[:space:]]|[^[:punct:]]'); So, any character other than alphanumerals, puntutation and space are to be considered as special characters.

REGEXP_LIKE is similar to the LIKE condition, except REGEXP_LIKE performs regular expression matching instead of the simple pattern matching performed by LIKE . This condition evaluates strings using characters as defined by the input character set.

REGEXP_SUBSTR extends the functionality of the SUBSTR function by letting you search a string for a regular expression pattern. It is also similar to REGEXP_INSTR , but instead of returning the position of the substring, it returns the substring itself.

REGEXP_MATCHES returns a set of text arrays, providing all matches of a regular expression pattern in a string. In contrast, REGEXP_MATCH returns a single-element text array for the first match, or NULL if there is no match.

regexp_like is a built-in function in MySQL that returns true if a given string matches the specified regular expression pattern. Otherwise, it returns false. It follows a syntax similar to other MySQL functions, making it easy to incorporate into your queries.