The correct way of doing it is to pass table from base workspace to the app as an input argument. In the Code View, In the top bar click add input arguments and type a name of the input argument (remember it can be any name, not necessary to be the name of your table). In this example, I suppose you named it inputTable. It is similar to adding a new input to a defined function. Next, you need to do two things
1) Pass the variable to the app:
During testing, you can pass the table to the app by pressing down arrow under Run button and typing the name of a table (this name should much the name of the table in the workspace).
If you are running the app directly, you can pass the input from command window as follow:
yourAppName(yourTable);
2) How to make the table accessible to all functions in your app
Create a public property by clicking the down arrow under Property button on the top bar in Code View. Give any suitable name to the property (in this example I suppose you named it appTable). In the startupFcn of your app, assign the inputTable to the public property appTable using the following syntax
app.appTable = inputTable;
Now you can access the table in any function of your App by referring it as app.appTable.
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You can directly access the variables from base workspace inside app designer without going through all of the above by using evalin(). Run the following lines in any function in ehich you want to access the table value
appTable = evalin('base', 'yourTable');
and then use appTable to access table value. But this method is not recommended. See why: https://www.mathworks.com/matlabcentral/answers/304528-tutorial-why-variables-should-not-be-named-dynamically-eval
