How to Extract Textual Content from a BLOB in Oracle SQL?

Retrieving Textual Content from BLOB in Oracle SQL

In Oracle SQL, BLOBs (Binary Large Objects) are used to store binary data such as images, audio, or other non-textual data. However, if you need to view the textual content stored within a BLOB from an SQL console, you can utilize the following techniques:

Firstly, it's worth noting that BLOBs are designed for binary data, and for storing text, CLOB (Character Large Object) or NCLOB (National Character Large Object) columns would be more appropriate. The query you provided would work if the BLOB contained CLOB data.

To view the textual representation of a BLOB, you can use the utl_raw.cast_to_varchar2() function:

select utl_raw.cast_to_varchar2(dbms_lob.substr(BLOB_FIELD)) from TABLE_WITH_BLOB where ID = '<row id>';

This query will retrieve the first 32767 characters (at most) of the text within the BLOB. Before performing the conversion, ensure that the character sets of the BLOB data, the database, and the VARCHAR2 variable are compatible to avoid potential data corruption.

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