MATLAB: Problems using SQL Queries within ButtonPushed callbacks

buttonpushedcallbackMATLABquerysql

Hi all,

I am experiencing an unusual problem within MATLAB App Designer.

I have a button that, when pushed, retrieves information from a database.

Without the SQL query, the ButtonPushed callback functions as expected, but when I add the code to execute the query, the ButtonPushed callback gets executed twice.

I found a solution is to move the SQL query into a separate function and call that from the ButtonPushed callback, but I am wondering why having it directly in the callback function is an issue.

Thanks in advance,

-Mac

Best Answer

Solved!

There was an EditField that somehow got mapped to the ButtonPushed callback.

This was the cause of the double trigger.

Thank you.

Related Solutions

MATLAB: How to take input from Edit Text Field and save the data with Push Button

Hi Keynan Hart,

For accessing database's within Matlab you will need Database Toolbox .

In the startUp function of the app, we create a connection to the database and store it in a variable. When the First Name and Last Name values are entered and Save to dB button is clicked. I have defined a SavetodBButtonPushed callback event which will utilize the connection established in the startUp function to write into the database

Some of the useful lines code are:

% Properties that correspond to app components
    properties (Access = public)
        UIFigure                 matlab.ui.Figure
        LastNameEditField        matlab.ui.control.EditField
        LastNameEditFieldLabel   matlab.ui.control.Label
        FirstNameEditField       matlab.ui.control.EditField
        FirstNameEditFieldLabel  matlab.ui.control.Label
        SavetodBButton           matlab.ui.control.Button
    end
    properties (Access = private)
        username; % Username for database
        password; % Password for database
        datasource; % For Database
        data; %data that would be written using sqlwrite
        tableName; %Name of the table in the database
        end
        
 methods (Access = private)
        % Code that executes after component creation
        function startupFcn(app)
            %Code for creating a connection to the database
            app.datasource = "MSSQLServerJDBCAuth"; % For Microsoft SQL Server Database
            % You will need to change it to your username and password of your dB.
            app.username = ""; 
            app.password = "";
            app.conn = database(app.datasource,app.username,app.password);
        end
        % Button pushed function: SavetodBButton
        function SavetodBButtonPushed(app, event)
            app.data = table(app.FirstNameEditField, app.LastNameEditField, 'VariableNames', {'First Name', 'Last Name'});
            app.tableName = 'UserInfo';
            sqlwrite(app.conn, app.tablename, app.data);
        end
end

For more information please visit:

App Designer

Getting started with Database toolbox

Connecting to the Database

database

sqlwrite

configureJDBCDataSource

select

MATLAB: Sql query find match

Mark - I suspect that your query could be more like

 sqlquery = ['select count(*) from db1 '...
             'where cname = ''' cname '''' ];

Note that since the name is a string, you should wrap it in quotes. For example, if cname were Mark, then the above SQL query would become

 sqlquery =
    select count(*) from db1 where cname = 'Mark'

Note that we use count to determine the number of records in the database that match on the name Mark. You could then execute this query as

 curs = exec(conn,sqlquery);
 curs = fetch(curs);
 curs.Data

where curs.Data would be an integer value that you would use to determine whether you should add the information to the database (if zero) or not (if non-zero).

Best Answer

Related Solutions

MATLAB: How to take input from Edit Text Field and save the data with Push Button

MATLAB: Sql query find match

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