[Gambas-user] Problem with MySQL LONGTEXT field type

[Luigi Carlotto]

Il giorno lun, 22/12/2008 alle 21.41 +0100, Luigi Carlotto ha scritto:

> Il giorno lun, 22/12/2008 alle 20.51 +0100, Luigi Carlotto ha scritto:
> 
> > Il giorno lun, 22/12/2008 alle 20.13 +0100, Luigi Carlotto ha
> > scritto:
> > 
> > > It pardons me, but the table in object is not part of mine
> > > database, but of the same motor of MySQL.
> > > The fact that is complete with the data, or without data, is not
> > > the true problem.
> > > My function reads the content of this table in order to determine
> > > the structure of a database, and not the data.
> > > The data contained in this table, come inserted automatically from
> > > the motor of MySQL, when they come created objects in the
> > > database.
> > > 
> > > In the normal situation, the table contains the information
> > > approximately the structure of the objects that MySQL creates of
> > > default, when it comes created database any.
> > > The table “routines” is of property of the “information_schema”
> > > schema, that it is of property of MySQL, and on which writing
> > > operations cannot be made, but only of reading.
> > > The same library of Gambas2, uses this table for populate the
> > > objects “Table”, “Field”, etc
> > > 
> > > To this point, it still pardons me, I I do not believe that to
> > > send the dump of this table he is of great usefullness since, if
> > > an installation of MySQL is had, it is possible to verify the
> > > problem directly.
> > > As creed of to have written, the problem does not seem that or
> > > caused from the reading of the field, but its maintenance in
> > > memory, if managed from a complex application… This, obviously, is
> > > only a hypothesis…
> > > 
> > > Thanks to you for the patience!
> > 
> > 
> > In attached the dump of the database of test.
> > A table is present only...
> > 
> > Thanks
> > 
> 
> 
> The dump it contains a single object of the database of test, a table,
> and only little records.
> As I have said, my application does not use the content of the table,
> but it gains its structure from the tables of system of MySQL.
> My application uses the structure of the database in order to
> represent in graphical way the layout of the database, the data is not
> useful to such scope.
> 
> In order to make this operation, it is connected to the database and,
> through the system tables, it gains the information of the structure
> of the database.
> The application can be connected to the types of database: PostgreSQL,
> MySQL and SQLite.
> Various from PostgreSQL, some tables of MySQL use fields of type
> longtext (blob), for which it is necessary to read these fields, for
> being able to determine, as an example: name of the field, type,
> dimensions, COMMENT, etc
> 
> This happens in the same way with bookcases of Gambas? I believe thus
> that or, at least from the reading of the code source. Also phpPgAdmin
> (PHP) executes query on these tables of system, in order to represent
> the objects contained in the database; same thing in phpMyAdmin.
> 


I have executed of the tests, to line of commando from Linux, in order
to understand the reason for which in Gambas they do not come loaded the
fields “longtext” from the database “information_schema” with MySQL.

The error, to how much seems, does not seem derived from an anomaly of
Gambas, but from an anomaly of MySQL, that is, executing the logon and
the query on the table “information_schema”, like customer root (and
with the commando “mysql”), the data come extracted all in complete and
corrected way; if the same operation comes carried out with an other
customer (not administrative), the type fields “longtext” they turn out
NULL.

I have verified the same thing with Gambas and, in effects, it is
behaved in the same way.
I have controlled the MySQL logon parameters, so as to verify if some
various formulation between the several customers exists, but have not
found some difference.
I have verified if the behavior were identical in phpMyAdmin (a program
PHP of management for MySQL), but strangely, the data comes always
visualized in corrected way, with any customer.

I have controlled code PHP, but some formulation does not exist, that it
can condition such behavior.
To this point, the anomaly sure is caused from MySQL, but I do not
succeed to understand like resolving the problem.
Also I have tried to give GRANT to the customers, but for the outline
“information_schema” it is not possible, since this is a database of
system.

How it is possible to resolve this problem?