PL/SQL UTL_ENCODE.BASE64_ENCODE

The UTL_ENCODE.BASE64_ENCODE function is part of the Oracle UTL_ENCODE package, used to encode binary data into a Base64 string. Base64 encoding is a widely used method for encoding binary data into an ASCII string format, ensuring safe transmission or storage in environments that handle text.

The UTL_ENCODE.BASE64_ENCODE function is typically used when binary data (e.g., files, images, or binary columns) needs to be represented as text for compatibility with systems that cannot handle raw binary data directly. Examples include embedding binary content in XML or JSON or transmitting binary files via email protocols like MIME.

Syntax

FUNCTION BASE64_ENCODE (
   r IN RAW
) RETURN RAW;

Parameters
r: The input RAW data to be Base64-encoded. This represents the binary content you want to encode.

Return Value

The function returns a RAW value that represents the Base64-encoded form of the input.

Usage Notes

Input and Output Format: Since the input and output are of type RAW, the caller often needs to handle conversions between RAW and VARCHAR2 for easier manipulation or display.

Chunk Size: Ensure the input RAW data does not exceed the size limits of the RAW data type in Oracle (32767 bytes in PL/SQL and 2000 bytes in SQL).

Decoding: To reverse the process, use UTL_ENCODE.BASE64_DECODE.

Examples

1. Encoding a String

To encode a string into Base64, convert it to RAW first:

DECLARE
   input_string VARCHAR2(100) := 'Hello, World!';
   raw_input    RAW(100);
   base64_raw   RAW(200);
   base64_text  VARCHAR2(200);
BEGIN
   -- Convert string to RAW
   raw_input := UTL_RAW.CAST_TO_RAW(input_string);
   
   -- Encode to Base64
   base64_raw := UTL_ENCODE.BASE64_ENCODE(raw_input);
   
   -- Convert RAW to VARCHAR2 for display
   base64_text := UTL_RAW.CAST_TO_VARCHAR2(base64_raw);
   
   DBMS_OUTPUT.PUT_LINE('Base64 Encoded String: ' || base64_text);
END;

Output:

Base64 Encoded String: SGVsbG8sIFdvcmxkIQ==

2. Encoding a BLOB

To encode the contents of a BLOB:

DECLARE
   blob_data    BLOB;
   raw_data     RAW(32767);
   base64_raw   RAW(32767);
   base64_text  VARCHAR2(32767);
BEGIN
   -- Load BLOB data (example: retrieving from a table)
   SELECT file_blob INTO blob_data FROM files_table WHERE file_id = 1;
   
   -- Convert a portion of BLOB to RAW
   DBMS_LOB.READ(blob_data, LENGTH(blob_data), 1, raw_data);
   
   -- Encode RAW to Base64
   base64_raw := UTL_ENCODE.BASE64_ENCODE(raw_data);
   
   -- Convert RAW to VARCHAR2 for display
   base64_text := UTL_RAW.CAST_TO_VARCHAR2(base64_raw);
   
   DBMS_OUTPUT.PUT_LINE('Base64 Encoded BLOB: ' || base64_text);
END;

Common Use Cases

1. Transmitting Binary Data in Text-Based Formats:

Embedding images or files in XML or JSON documents.
Sending binary data via email attachments (MIME encoding).

2. Storing Binary Data as Text:

Saving binary data in text-based databases.

Interfacing with External Systems:

Encoding data for APIs or services requiring Base64 representation.

Important Considerations

Efficiency: Base64 encoding increases the size of the data by approximately 33%. Ensure you account for this overhead when storing or transmitting data.

Security: Base64 encoding is not encryption. For secure transmission, use encryption methods like DBMS_CRYPTO in addition to Base64.

By leveraging the UTL_ENCODE.BASE64_ENCODE function, developers can seamlessly handle binary-to-text transformations in Oracle PL/SQL environments.