Wrong MySQL query result when accessing through Matlab

I'm accessing MySQL through Matlab, using the following code:

dbName      = 'dbName' ;
DB.(dbName) = database(dbName,'user','password');
 
openDateTimeStr = '2006-03-17 00:00:00';
timeZoneOpen    = 'GMT';
 
queryStr   = ['SELECT CONVERT_TZ(''' openDateTimeStr ''', ''' timeZoneOpen ''', ''GMT'')'];
 
setdbprefs('datareturnformat', 'cellarray')
curs     = exec(DB.(dbName), queryStr);
curs     = fetch(curs);
result   = curs.Data;
close(curs);

and I get the following result, which is 1 hour earlier than what it should be:

result = 1×1 cell array
        {'2006-03-16 23:00:00.0'}

But when I type the exact same query directly into MySQL Workbench, I get the correct result:

SELECT CONVERT_TZ('2006-03-17 00:00:00', 'GMT', 'GMT')  
      -> '2006-03-17 00:00:00'

On the other hand, if I do the same request but for an earlier date (eg: 2006-01-06) both queries (Matlab and MySQL Workbench) return the same (correct) result.

Hence it seems to me like a sort of daylight savings issue that's generating a problem when I access MySQL through Matlab, but not when I access MySQL through it's Workbench.

Any ideas on what might be going on? and how to fix this?

[Walter Roberson]

Odd.

What is your local timezone ? I am wondering if the interface is converting the time returned to local time.

[Rodrigo Cerda]

I'm on Santiago de Chile, which is currently on GMT-3.

An in fact, Chile switches between GMT-3 and GMT-4 in March every year, bacause of daylight savings.

But the strange thing is that the problematic query requests actually no conversion, since it's converting from GMT to GMT.