Text field showing as blob in DBGrid
lazarus / 16-Databases

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dkjMusic · 2011-01-19 01:39

Has there been any fix to this yet? Is there any way to display the
text?

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Phil · 2011-01-19 01:46

Not sure what you mean. Are you referring to a bug report?

Thanks.

-Phil

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dkjMusic · 2011-01-19 02:41

Quote from: Phil on January 19, 2011, 02:46:32 amNot sure what you
mean. Are you referring to a bug report?

Thanks.

-Phil

When I fill a DBGrid with a query on a MySQL database, integer and
date fields show correctly but text fields show as "(blob)". I was
wondering if there is a way to have text fields displayed correctly.
Googling showed this had been a problem in the recent past and I was
wondering whether there is a solution yet.

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Phil · 2011-01-19 02:54

Are you using the components from the SQLdb tab? That's a separate
package, I think.

I haven't used MySQL, but those components work with Sqlite text
fields (VARCHAR).

Thanks.

-Phil

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dkjMusic · 2011-01-19 03:10

Quote from: Phil on January 19, 2011, 03:54:36 amAre you using the
components from the SQLdb tab? That's a separate package, I think.

I haven't used MySQL, but those components work with Sqlite text
fields (VARCHAR).

Thanks.

-Phil

Yes, I'm using the SQLdb components. If DBGrid will display SQLite
text fields, I'll check it out. Thanks for your input.

That is, if I can figure out why I get "/usr/bin/ld: cannot find
-lsqlite" when I try to install the SQLite packages.

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Phil · 2011-01-19 03:24

I created my Sqlite database from XML and in the code for doing that I
find this comment:

"Note can't use TEXT or REAL as data type for some reason with
TSqlite3Dataset".

That's why I created the text fields a VARCHAR. Maybe that limitation
has something to do with your problem as well.

I'm on Mac, where all Macs have Sqlite already installed, so I don't
think I can help you much with installing it.

Thanks.

-Phil

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Lacak2 · 2011-01-20 06:32

This problem was already discussed :
http://lazarus.freepascal.org/index.php/topic,5321.msg56151.html#msg56
151

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dkjMusic · 2011-01-20 11:41

Quote from: Lacak2 on January 20, 2011, 07:32:36 amThis problem was
already discussed :
http://lazarus.freepascal.org/index.php/topic,5321.msg56151.html#msg56
151
I know. That's why my post asked "Has there been any fix to this yet?"

Anyway, Phil's replies got me to look at SQLite. I was using a MySQL
database, converted from MSAccess with Kexi, and I'm now using a
SQLite version and don't have to mess with a server and user account
administration. PLUS the Sqlite3Dataset1 with DBGrid now shows the
Text fields just fine, which solves my original problem. Thanks to
Phil for putting me on the right track.

I'm new to Lazarus and database programming and appreciate the help
from all of you.

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cpalx · 2011-01-20 14:54

cast your field

do something like this:

select cast(yourfield as varchar) as name  from table

that will solve your problem

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Phil · 2011-01-20 15:28

Does that work with Sqlite too? That might explain why I couldn't use
TEXT fields.

Thanks.

-Phil

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jamj · 2011-02-20 11:03

I had the same problem. Finally I have solved the problem. 

For some reason the mysql components do not realize that text and blob
data are diferent so for the libraries is the same type.

When you receive the "blob" the data is still there, you only have to
extract the data with a cast. I did this to get the data:

var
e : string;

begin
  e:= MY_QUERY.Fields[1].AsString;

Where "fields" represents the colum 1 data. MY_QUERY is a TSQLquery
component.