SQL function help

Question

Hi, I am trying to write a sql query to replace the string starting with '<' with NULL. Right now I am using CASE statement to replace with NULLs. Is there any function to replace with NULLs for all the strings starting with '<%'.
Example:
CASE When field_name LIKE '<%' then NULL else field_name
(before) After
<NA> NULL
<UK> NULL
I want to replace the above sql suery with a single sql function without using CASE statements.
I tried to use REPLACE function, but it replaces only single character. I want to replace the whole string
Thanks in advance.

Answer 1

Hi,
Adam Martin posted a good solution. I hope that it is clear to you that you have to replace the string '<NA>' with your column(s).
I.e.:
SELECT REGEXP_REPLACE (a.col1, '^<.?+', '') AS col1
     , REGEXP_REPLACE (a.col2, '^<.?+', '') AS col2
  FROM table1 a;
{code}
You can use also the DECODE and SUBSTR functions to have the same result:
The code below will get the first character with SUBSTR function and the DECODE function will return NULL if the value of the first character is "<" otherwise the value of the column.
{code:sql}
SELECT DECODE(SUBSTR(a.col1,1,1),'<', NULL, a.col1) AS col1
     , DECODE(SUBSTR(a.col2,1,1),'<', NULL, a.col2) AS col2
  FROM table1 a;
{code}
but using REGEXP_REPLACE is easier to write.