How Can I Extract Text from Oracle SQL BLOBs?

Extracting Textual Contents from Oracle SQL BLOBs

When working with Oracle SQL, you may encounter situations where you need to retrieve and view the text contained within a BLOB (Binary Large Object). The default query for retrieving BLOB fields only returns a reference to the BLOB's memory location, which is not the desired text representation you're looking for.

To retrieve textual contents from a BLOB in Oracle SQL, you can utilize the combination of utl_raw.cast_to_varchar2() and dbms_lob.substr() functions as follows:

<br>SELECT utl_raw.cast_to_varchar2(dbms_lob.substr(BLOB_FIELD))<br>FROM TABLE_WITH_BLOB<br>WHERE ID = '<row id>';<br>

This query will cast the BLOB content to a VARCHAR2 datatype, allowing you to view the text. However, note that it has a limitation in that it can only retrieve a maximum of 32767 characters.

Alternatively, consider storing text data in CLOB/NCLOB columns instead of BLOBs, as they are specifically designed for storing character-based data. Queries against CLOB fields would directly return text without the need for additional casting.

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