Oracle functions are built into Oracle and are available for use in various appropriate Oracle statements. You can also create your own function using PL/SQL.
| Function | Description |
|---|---|
| ASCII | Returns the NUMBER code that represents the specified character. |
| ASCIISTR | Converts a string in any character set to an ASCII string using the database character set. |
| CHR | Returns the character based on the NUMBER code. |
| COMPOSE | Returns a Unicode string. |
| CONCAT | Concatenate two strings together. |
| Concat with || | Concatenate 2 or more strings together. |
| CONVERT | Converts a string from one character set to another. |
| DECOMPOSE | Accepts a string and returns a Unicode string. |
| DUMP | Returns a varchar2 value that includes the datatype code. |
| INITCAP | Sets the first character in each word to uppercase and the rest to lowercase. |
| INSTR | Returns the location of a substring in a string. |
| INSTR2 | Returns the location of a substring in a string, using UCS2 code points. |
| INSTR4 | Returns the location of a substring in a string, using UCS4 code points. |
| INSTRB | Returns the location of a substring in a string, using bytes instead of characters. |
| INSTRC | Returns the location of a substring in a string, using Unicode complete characters. |
| LENGTH | Returns the length of the specified string. |
| LENGTH2 | Returns the length of the specified string, using UCS2 code points. |
| LENGTH4 | Returns the length of the specified string, using UCS4 code points. |
| LENGTHB | Returns the length of the specified string, using bytes instead of characters. |
| LENGTHC | Returns the length of the specified string, using Unicode complete characters. |
| LOWER | Converts all letters in the specified string to lowercase. |
| LPAD | Pads the left-side of a string with a specific set of characters (when string1 is not null). |
| LTRIM | Removes all specified characters from the left-hand side of a string. |
| NCHR | Returns the character based on the number_code in the national character set. |
| REGEXP_INSTR | Returns the location of a regular expression pattern in a string. |
| REGEXP_REPLACE | Replace a sequence of characters in a string with another set of characters using regular expression pattern matching. |
| REGEXP_SUBSTR | Extract a substring from a string using regular expression pattern matching. |
| REPLACE | Replaces a sequence of characters in a string with another set of characters. |
| RPAD | Pads the right-side of a string with a specific set of characters (when string1 is not null). |
| RTRIM | Removes all specified characters from the right-hand side of a string. |
| SOUNDEX | Returns a phonetic representation (the way it sounds) of a string. |
| SUBSTR | Extract a substring from a string. |
| TRANSLATE | Replaces a sequence of characters in a string with another set of characters. |
| TRIM | Removes all specified characters either from the beginning or the end of a string. |
| UPPER | Converts all letters in the specified string to uppercase. |
| VSIZE | Returns the number of bytes in the internal representation of an expression. |