SQL: Visual QuickStart Guide

Extracting a Substring with SUBSTRING()

Use the SUBSTRING() function to extract part of a string. The SUBSTRING() function’s important characteristics are:

• A substring is any sequence of contiguous characters from the source string, including an empty string or the entire source string itself.

• SUBSTRING() extracts part of a string starting at a specified position and continuing for a specified number of characters.

• A substring of an empty string is an empty string.

• If any argument is null, SUBSTRING() returns null. (But see the Oracle exception in the DBMS Tip in this section.)

To extract a substring:

• Type:

  SUBSTRING(string FROM start
  [FOR length])
  

  string is the source string from which to extract the substring. string is a string expression ...