regexp_replace string

Question

I'm using regexp_replace to standardize mailing addresses and I've encountered a situation I'm having trouble with.

Consider the following two addresses and what their result should be:

• 115 1/2 East 6th St -> 115 1/2 E 6th St
• 818 East St -> 818 East St

In the second address, "East" is the actual name of the street, not a directional indicator.

For my query, I've attempted

SELECT
     regexp_replace(address, 'East[^ St]', 'E ')

but this fails to convert the first address to it's proper format.

How can I write my regexp_replace such that the word East is converted to an 'E' in the first address, but leaves the word intact in the second address?

Answer 1

Your current pattern matches the literal text East followed by any single character that isn't space, S , or t . I'm assuming you probably meant to use a negative lookahead to make sure that "East" doesn't come before " St", but sadly Oracle doesn't support negative lookaheads. Instead, you'll need to make the REGEXP_REPLACE conditional:

CASE
    WHEN address LIKE '%East%' AND address NOT LIKE '%East St%'
        THEN REGEXP_REPLACE(address, your_pattern, your_replacement)
    ELSE address
END

Answer 2

This answers your question with REGEXP_REPLACE(). It looks for the string ' EAST' (don't want to catch the case where 'east' is the end of another word) followed by a space, one or more characters, another space and the string 'St' which is remembered in a group. If found, replace it with ' E' followed by the second remembered group (the space followed by the one or more characters followed by the space and 'St' . This is needed as they are 'consumed' by the regex engine as it moves left to right analyzing the string so you need to put them back. Note I added a bunch of different test formats (always test for the unexpected too!):

SQL> with tbl(address) as (
     select '115 1/2 East 6th St'       from dual union
     select '115 1/2 NorthEast 6th St'  from dual union
     select '115 1/2 East 146th St'     from dual union
     select '115 1/2 East North 1st St' from dual union
     select '818 East Ave'              from dual union
     select '818 Woodward'              from dual union
     select '818 East St'               from dual
   )
   select regexp_replace(address, '( East)( .+ St)', ' E\2') new_addr
   from tbl;

NEW_ADDR
------------------------------------------------------------------------
115 1/2 E 146th St
115 1/2 E 6th St
115 1/2 E North 1st St
115 1/2 NorthEast 6th St
818 East Ave
818 East St
818 Woodward

7 rows selected.