Difference of SCAN and SUBSTR

• SCAN extracts words within a value that is marked by delimiters.
  
  
• SUBSTR extracts a portion of a value by starting at a specified location. 

The SUBSTR function is the best choice to extract class level information from ID. By contrast, the SCAN function is best used when

• you know the order of the words in the character value
• the starting position of the words varies
• the words are marked by some delimiter. 

General form, SCAN function:

SCAN(argument,n,<delimiters>)

where

• argument specifies the character variable or expression to scan.
  
  
• n specifies which word to read.
  
  
• delimiters are special characters that must be enclosed in single quotation marks (' '). If you do not specify delimiters, default delimiters are used.

General form, SUBSTR function:

SUBSTR(argument,position,<n>)

where

• argument specifies the character variable or expression to scan.
  
  
• position is the character position to start from.
  
  
• n specifies the number of characters to extract. If n is omitted, all remaining characters are included in the substring.