Function to intercept string in oracle

Oracle provides two string interception functions: substr(): intercepts characters of the specified length starting from the specified position. substring(): intercept the remaining characters from the specified position, or intercept the characters of the specified length from the specified position.

String interception function in Oracle

In order to facilitate the interception of strings, Oracle provides two functions, substr() and substring. (), their usage is similar.

substr(string, start, length)

Truncate length characters starting from the start character from the string string.

Example:

SELECT substr('Hello World', 6, 5) FROM dual;
-- 输出：World

substring(string, start [, length])

Intercept from string string A string starting with the start character. If length is not specified, truncates to the end of the string.

Example:

SELECT substring('Hello World', 6) FROM dual;
-- 输出：World

SELECT substring('Hello World', 2, 3) FROM dual;
-- 输出：ell

Note:

• start parameter starts from 1, indicating the number 1 in the string a character.
• If start or length is negative, the function returns an empty string.
• If start exceeds the string length, the function will return an empty string.
• If length exceeds the length of the string, the function will truncate to the end of the string.

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