How do I proceed after selecting something from a combo box?

[#1]

 //fruit is a row in my table
 nw = New window ("Select fruit",
 cb = combo box ("apple", "Mango", "Banana")
 cb << Set Selected,
 << Set Width (20),
 //Here I select apple
 Button Box ("OK",
 	table1 << SelectWhere(:fruit!=apple) << Delete Rows;
 ) )

How do I proceed with the analyses by only selecting data corresponding to 'apple'

Here is what I want from this code:

1, I first make a combo box

2. Select apple from the combo box

3. Once I click "OK" I should have the other rows deleted and only rows with apple left.

[#2]

You could do something like this.

table1 = New Table( "Kind of Fruity",
	Add Rows( 6 ),
	New Column( "fruit", Character, "Nominal", Set Values( {"Apple", "Banana", "Mango", "Apple", "Apple", "Banana"} ) ),
	New Column( "Condiment",
		Character,
		"Nominal",
		Set Values( {"Peanut Butter", "Ketchup", "Cayenne Pepper", "Chocolate Fudge", "Caramel", "Salt"} )
	)
);
nw = New Window( "Select fruit",
	cb = Combo Box( {"Apple", "Mango", "Banana"} ),
	Button Box( "OK",
		table1 << Delete Rows( table1 << Get Rows Where( :fruit != (cb << Get Selected) ) );
		nw << Close Window;
	)
);

[#3]

You need slight modifications to your script:

• You need to use list to input values to combo box
• You should get the value which was selected by user (usually within OK button) using << get selected
• You should perform the check dynamically based on the user selection in your Select Where statement

@mmarchandTSI answer already has answer for these problems so I provide a bit different solution in which you get the values based on your fruit column to the combo box, demonstrate how to set specific fruit and use << get rows where instead of select where

Names Default To Here(1);

dt = New Table("Untitled",
	Add Rows(5),
	Compress File When Saved(1),
	New Column("fruit",
		Character,
		"Nominal",
		Set Values({"apple", "Mango", "Banana", "apple", "Banana", "Kiwi"})
	)
);
Summarize(dt, fruits = By(:fruit));

nw = New Window("Select fruit",
	cb_fruits = Combo Box(fruits),
	Button Box("OK",
		sel_fruit = cb_fruits << get selected;
		nok_fruit_rows = dt << Get Rows Where(:fruit != sel_fruit);
		dt << Delete Rows(nok_fruit_rows); // note that fruits variable isn't updated
		nw << Close Window; 
	),
	cb_fruits << Set(Contains(fruits, "Kiwi"));
);