How do I convert from BLOB to TEXT in MySQL?

Converting large BLOBs: avoiding hiccups

If you're wrestling with large BLOBs, ensure your server parameters can stomach large packet sizes:

max_allowed_packet=16M
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Save yourself from choking! Increase the max_allowed_packet size in your MySQL configuration.

When CAST isn't just for broken bones

CONVERT isn't the only game in town. Step into the CAST function, another great tool for conversion:

SELECT CAST(blob_col AS CHAR(65535) CHARACTER SET utf8) AS text_col FROM table_name;
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It's straightforward, like putting on a CAST; it turns the BLOB into a CHAR text type, ensuring a smooth healing process – uh, sorry – I mean no data truncation.

Checking the mirror after surgery

After the conversion, don't forget to do a thorough check to confirm the data's integrity:

SELECT LENGTH(blob_col) AS original_length, LENGTH(text_col) AS converted_length FROM table_name;
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Just like checking the mirror after a facelift, you want to look for any signs of data mishandling.

Step-by-step BLOB swap

Sometimes, you might want to add a new TEXT column, carefully transfer data from the BLOB column, and let the old BLOB rest in peace:

ALTER TABLE table_name ADD COLUMN text_col TEXT;

UPDATE table_name 
SET text_col = CONVERT(blob_col USING utf8);

ALTER TABLE table_name DROP COLUMN blob_col; 
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This approach is like when you put your old records in the attic box and start using Spotify. You move the music, but not the vinyl crunch.

Encoding dilemmas: Spoilt for choices

UTF8 usually strikes the right balance between compatibility and storage efficiency, but it might let you down when you need a wide range of characters. In this case, go impress your friends with UTF16.

Be aware, you don't want to lose your binary data in the TEXT format due to poor character set choice. When in doubt, go with base-64 encoding:

SELECT TO_BASE64(blob_col) AS base64_text FROM table_name;
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...and bring it back with:

SELECT FROM_BASE64(base64_text) AS original_text FROM table_name;
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Voilà! Properly preserved binary data in text format.

Large dataset management: Preventing an eyelid twitch

When handling large datasets, employing a batch-processing script can give your server much-needed breaks:

# Psuedocode for a batch-processing script
while the records hold:
  convert a batch of records from BLOB to TEXT
  check the conversion with a magnifying glass
  pin a flag on the progress map 
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This will work for you even if the dataset seems as large as Santa's "Naughty and Nice" list!

GUI to the rescue: MySQL Workbench

A tool like MySQL Workbench can be a boon for making this process less daunting and more manageable:

1. Inspect the new TEXT column after executing your conversion queries.
2. Be on a lookout for unexpected outcomes or alterations in your textual data.

Who said making conversions need to feel like a handwriting contest with a broken wrist?

Golden rules of conversion

Remember, a gentle and tailored approach to character set, conversion method, and batch processing will make your text conversion sail smoothly like Swan Lake.