Oracle PL/SQL Programming, Third Edition

Name

LTRIM

Synopsis

The LTRIM function is the opposite of LPAD. Whereas LPAD adds characters to the left of a string, LTRIM removes, or trims, characters from the left of the string. And just like LPAD, LTRIM offers much more flexibility than simply removing leading blanks. The specification of the LTRIM function is:

FUNCTION LTRIM (string1 IN VARCHAR2 [, trim_string IN VARCHAR2])
RETURN VARCHAR2

LTRIM returns string1 with all leading characters removed up to the first character not found in the trim_string. The second parameter is optional and defaults to a single space.

There is one important difference between LTRIM and LPAD. LPAD pads to the left with the specified string, and repeats that string (or pattern of characters) until there is no more room. LTRIM, on the other hand, removes all leading characters that appear in the trim string, not as a pattern, but as individual candidates for trimming.

Here are some examples:

• Trim all leading blanks from " Way Out in Right Field”:

  LTRIM ('    Way Out in Right Field') --> 'Way Out in Right Field'

  Because we did not specify a trim string, it defaults to a single space, so all leading spaces are removed.

• Remove all numbers from the front of the string:

  my_string := '70756234LotsaLuck';
  
  LTRIM (my_string, '0987612345') --> 'LotsaLuck'

  By specifying every possible digit in the trim string, we ensure that any and all numbers will be trimmed, regardless of the order in which they occur (and the order in which we place them in the trim string). ...