Question

I have TABLE1 with columns COL1,COL2 defined as LongVarChar in Oracle.

Every time user loads a record to TABLE1, COL1 will have the old value and COL2 will have the old value + new value. i.e.

For ex:

COL1            COL2
                Bat
Bat             Bat Ball
Bat Ball        Bat Ball Wicket
Bat Ball Wicket Bat Ball Wicket Stump

To get the only new value, i am planning to delete contents of COL2 from COL1 contents..I think this is a pretty bad idea..

I tried the usual “-” operator and it says "Expected Numeric but received CLOB"

But does any one any better idea or how to accomplish this?

Thanks so much

Answer 1

Assuming you mean Varchar2, and (as in your example), each old value is separated by an additional space, then something like this should work:

SELECT SUBSTR(col2, NVL(LENGTH(col1)+2,0)) "New Value" FROM TABLE1

eg:

select substr('Bat', nvl(length(null)+2,0)) from dual;

results in ‘Bat’

select substr('Bat Ball', nvl(length('Bat')+2,0)) from dual;

results in ‘Ball’

---

But if you’re actually talking about a CLOB datatype, then substitute:

dbms_lob.substr( colX, 4000, 1) 

instead of colX (where X is 1 or 2)

[This will give you the first 4000 bytes of the CLOB – in order to get more, you’d have to use PL/SQL]