In oracle/PLSQL the substr functions allows you to extract a substring from a string
The syntax for the substr function is:
substr( string start_position [ length ] )
说明
string is the source string
start_position is the position for extraction The first position in the string is always
length is optional It is the number of characters to extract If this parameter is omitted substr will return the entire string
For example:
substr(This is a test ) would return is
substr(This is a test ) would return is a test
substr(TechOnTheNet ) would return Tech
substr(TechOnTheNet ) would return Net
substr(TechOnTheNet ) would return The
substr(TechOnTheNet ) would return On
