What exactly is a BLOB

[hightechfarmer]

I am new to MySQL. Can someone shed some light for me as to what a BLOB is. The documentation does not quite do it for me. I realize you can store stuff like graphics in that field, but that does not make much sense now either. How do you instert a image into a database field?
Excuse my newbieness!

Chad

[toma42]

Binary Large OBject. You can insert an image because a blob can store binary info

[terje-s]

Like Tom says, BLOB stands for Binary Large OBject. You also have the type LONGBLOB, wich allows more data to be stored (I'm not certain of the limits in any of them). However, if you are to insert a relatively large image in your DB, you should probably go for longblob.

You insert an image to your database just like you would insert anything else; with an INSERT statement. Consider this:

CREATE TABLE temp (
id int(11) default '0' not null auto_increment primary key,
image_data longblob
);

Then you could read the data from say a .gif file, and insert it to this table;

INSERT INTO temp VALUES ('', '<data-read-from-file');

At a later time, you can retrieve this data and do whatever you want with it. A popular choice when using php, is to output the header "Content-type: image/gif", and then simply print the image_data field from the database.

[toma42]

A popular choice when using php, is to output the header "Content-type: image/gif", and then simply print the image_data field from the database.

This is true, but the problem here is the popular way is very wrong.

I strongly recommned not storing just image data in the database, but a path to an image stored under documentroot instead.

If you're using this for uploading weird file formats like .doc or .xls to link to some other data, then you're using a blob the way it should be used.