How to Update Blob Column In Oracle 12C?

To update a blob column in Oracle 12c, you can use the UPDATE statement with the SET clause. First, you need to convert the blob data into a readable format using the UTL_RAW package. Then, you can update the blob column by specifying the new data in the SET clause of the UPDATE statement. Make sure to use the WHERE clause to specify the condition for which records to update. Additionally, consider the size limitations of the blob column when updating large amounts of data. After executing the UPDATE statement, the blob column will be updated with the new data provided.

What is the purpose of using a blob column in Oracle 12c?

In Oracle 12c, a blob column is typically used to store large binary data, such as images, videos, documents, etc. It allows users to store and manipulate large amounts of data efficiently, without having to worry about data size limitations.

Some common use cases for a blob column in Oracle 12c include:

1. Storing and retrieving large files or documents
2. Storing and managing multimedia data, such as images or videos
3. Storing data that needs to be accessed quickly and efficiently, such as application logs or metrics

Overall, the purpose of using a blob column in Oracle 12c is to provide a flexible and efficient way to store and manage large binary data within the database.

How to update a blob column with a compressed file in Oracle 12c?

To update a blob column with a compressed file in Oracle 12c, you can follow these steps:

1. Compress the file: First, you need to compress the file that you want to store in the blob column. You can use a tool like WinZip or gzip to compress the file.
2. Convert the compressed file to a blob: Once you have the compressed file, you need to convert it to a blob data type. You can do this using the DBMS_LOB package in Oracle. Here is an example of how you can do this:

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DECLARE
    l_blob BLOB;
    l_bfile BFILE := BFILENAME('DIRECTORY','FILENAME.ZIP');
BEGIN
    INSERT INTO your_table (blob_column)
    VALUES (empty_blob())
    RETURNING blob_column INTO l_blob;

    DBMS_LOB.fileopen(l_bfile, DBMS_LOB.file_readonly);
    DBMS_LOB.loadfromfile(l_blob, l_bfile, DBMS_LOB.getlength(l_bfile));
    DBMS_LOB.fileclose(l_bfile);
END;
/

In the above example, replace 'DIRECTORY' with the directory where the compressed file is located, and 'FILENAME.ZIP' with the name of the compressed file.

1. Update the blob column: Finally, you can update the blob column in your table with the compressed file data. You can do this using a simple UPDATE statement. Here is an example:

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UPDATE your_table
SET blob_column = l_blob
WHERE your_condition;

In the above example, replace 'your_table' with the name of your table, 'blob_column' with the name of your blob column, and 'your_condition' with any conditions you want to apply to update specific rows.

By following these steps, you can successfully update a blob column with a compressed file in Oracle 12c.

How to update a blob column with an image file in Oracle 12c?

To update a blob column with an image file in Oracle 12c, you can use the PL/SQL package DBMS_LOB to read the image file and insert it into the blob column. Here is an example of how you can do this:

1. First, create a table with a blob column to store the image:

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CREATE TABLE images (
    id NUMBER PRIMARY KEY,
    image_data BLOB
);

1. Next, create a PL/SQL block to read the image file and update the blob column:

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DECLARE
    l_blob BLOB;
    l_bfile BFILE := BFILENAME('DIRECTORY_NAME', 'IMAGE_FILE.jpg');
BEGIN
    INSERT INTO images (id, image_data) VALUES (1, EMPTY_BLOB()) RETURNING image_data INTO l_blob;
    
    DBMS_LOB.FILEOPEN(l_bfile, DBMS_LOB.FILE_READONLY);
    DBMS_LOB.LOADFROMFILE(l_blob, l_bfile, DBMS_LOB.GETLENGTH(l_bfile));
    DBMS_LOB.FILECLOSE(l_bfile);
    
    COMMIT;
END;
/

In this code snippet, replace 'DIRECTORY_NAME' with the directory name where the image file is stored, and 'IMAGE_FILE.jpg' with the name of the image file you want to store in the blob column. This code block will insert the image file into the blob column of the images table.

1. Execute the PL/SQL block to update the blob column with the image file.

After running the above code snippet, the blob column in the images table will be updated with the image file specified in the PL/SQL block. You can verify the update by selecting the data from the images table.

How to handle null values in a blob column when updating in Oracle 12c?

When updating a blob column in Oracle 12c, you can handle null values by using the following methods:

1. Using a NULL value: You can set the blob column to NULL if you want to remove the existing data in the column. This can be done by simply setting the blob column to NULL in the UPDATE statement.

Example:

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UPDATE table_name
SET blob_column = NULL
WHERE <condition>;

1. Using the EMPTY_BLOB() function: If you want to replace the existing data with an empty blob value, you can use the EMPTY_BLOB() function in the UPDATE statement.

Example:

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UPDATE table_name
SET blob_column = EMPTY_BLOB()
WHERE <condition>;

1. Using a placeholder value: If you want to update the blob column with a specific value for null values, you can use a placeholder value in the UPDATE statement.

Example:

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UPDATE table_name
SET blob_column = TO_BLOB('Your placeholder value')
WHERE blob_column IS NULL;

By using these methods, you can handle null values in a blob column when updating in Oracle 12c.