Databases Reference
In-Depth Information
If we now browse the table, we can see the field length information,
[BLOB - 0 B]
,
for each
BLOB
field:
This is because the
$cfg['ShowBlob']
configuration directive is set to
FALSE
by
default, thus blocking the display of
BLOB
contents in Browse and Edit modes (and
showing a
Binary - do not edit
warning). This behavior is intentional—usually we
cannot do anything with binary data represented in plain text.
Binary Contents Uploads
If we now edit one row, we see the warning and a
Browse…
button. The exact
caption on this button depends on the browser. Even though editing is not allowed,
we can easily upload a text or binary file's contents into this
BLOB
column.
Let's choose an image file using the
Browse
button—for example, the
logo_left.png
file in a test copy of the
phpMyAdmin/themes/original/img
directory located on our
client workstation—and click
Go
.
We need to keep in mind some limits for the upload size. Firstly, the
BLOB
field size
is limited to 64K, so phpMyAdmin reminds us of this limit with the
Max: 65,536 Bytes
warning. Also, there could be limits inherent to PHP itself - see Chapter 8,
Importing
Structure and Data
- which would be also taken into account in this maximum size
value. We have now uploaded an image inside this field for a specific row:
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