Oracle SQL Extracting A Value From Another Column into a New Column?

Question

Basically I am trying to create a table with a column whose values are extracted from the zipcode portion of an address column in a separate table. The address column is a string that includes street address,city,state, and zipcode each separated by a comma.

FYI The comma format is consistent throughout the dataset.How do I go about setting this up? Below is the code I used to try and create the table.

CREATE TABLE CHILD_TABLE
 (ZipCode NUMBER REFERENCES 
  PARENT_TABLE(substr(address,instr(address,',',-1)+2)));

Answer 1

Here's one option which shows how to extract zipcode out of the address string - using regular expressions, take the last word :

SQL> with addr (addr) as
  2    -- this is the "address column"
  3    (select 'Muppet street,London,England,12345' from dual)
  4  select regexp_substr(addr, '\w+$') zipcode
  5  from addr;

ZIPCO
-----
12345

SQL>

[EDIT: insert ZIP codes into another table]

Here's how.

SQL> -- Table that contains addresses
SQL> create table t1 (addr varchar2(50));

Table created.

SQL> insert into t1
  2    select 'Muppet street,London,England,12345' from dual union all
  3    select 'Batman road,Berlin,Germany,9948'    from dual union all
  4    select 'Ilica,Zagreb,Croatia,10000'         from dual;

3 rows created.

SQL> -- A new table, containing ZIP codes
SQL> create table t2 (zipcode number);

Table created.

SQL> -- Insert zip codes from the address into the new table
SQL> insert into t2 (zipcode)
  2    select regexp_substr(t1.addr, '\w+$')
  3    from t1;

3 rows created.

SQL> select * From t2;

   ZIPCODE
----------
     12345
      9948
     10000

SQL>