How to query a CLOB column in Oracle

clob, ora-06502, oracle, plsql, sql

Solution

When getting the substring of a CLOB column and using a query tool that has size/buffer restrictions sometimes you would need to set the BUFFER to a larger size. For example while using SQL Plus use the `SET BUFFER 10000` to set it to 10000 as the default is 4000.

Running the `DBMS_LOB.substr` command you can also specify the amount of characters you want to return and the offset from which. So using `DBMS_LOB.substr(column, 3000)` might restrict it to a small enough amount for the buffer.

See oracle documentation for more info on the substr command

    DBMS_LOB.SUBSTR (
       lob_loc     IN    CLOB   CHARACTER SET ANY_CS,
       amount      IN    INTEGER := 32767,
       offset      IN    INTEGER := 1)
      RETURN VARCHAR2 CHARACTER SET lob_loc%CHARSET;

Problem

I'm trying to run a query that has a few columns that are a CLOB datatype. If i run the query like normal, all of those fields just have `(CLOB)` as the value. I tried using `DBMS_LOB.substr(column`) and i get the error ``` ORA-06502: PL/SQL: numeric or value error: character string buffer too small ``` How can i query the CLOB column?

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