Want to protect your cyber security and still get fast solutions? Ask a secure question today.Go Premium

  • Status: Solved
  • Priority: Medium
  • Security: Public
  • Views: 896
  • Last Modified:

How to work with blob field

Hello !
Plese guide me how to work (update, insert) with blob field in mysql. I do like to use mysql api, because its
platform independence.
thankyou very much
3 Solutions
Have a look here for a quickstart:

If you have some specific questions - feel free to ask.

I wrote up blob handling for vb at www.vbmysql.com/articles/blobaccessvb.html
It's won't help with the API, but it will help with some blob handling principles.
mysql blob fields are very easy to handle.

What you need to be sure of is you make use of mysql_real_escape before you insert any data into your blob field!

In order to retrieve data from the blob field, make sure you use mysql_fetch_lengths as that will give you the right size of the data stored in the blob field (unlike mysql_res->length which returns the max column length).  Calling strlen(mysqlRow[index]) will fail if your BLOB field contains binary data because you might have a NULL character somewhere.

ohh, also ... when you insert binary data into a blob field, make sure you use mysql_real_query() because as stated above, your blob data might contain a NULL characters and still be part of the data.  That's why you'll need to provide a length parameter to mysql_real_query().

here's a C example of how to do what I mentioned above ...

char query[1000],*end;

end = strmov(query,"INSERT INTO test_table values(");
*end++ = '\'';
end += mysql_real_escape_string(&mysql, end,"What's this",11);
*end++ = '\'';
*end++ = ',';
*end++ = '\'';
end += mysql_real_escape_string(&mysql, end,"binary data: \0\r\n",16);
*end++ = '\'';
*end++ = ')';

if (mysql_real_query(&mysql,query,(unsigned int) (end - query)))
   fprintf(stderr, "Failed to insert row, Error: %s\n",

Featured Post

Become an Android App Developer

Ready to kick start your career in 2018? Learn how to build an Android app in January’s Course of the Month and open the door to new opportunities.

Tackle projects and never again get stuck behind a technical roadblock.
Join Now