As you know Visual Studio LightSwitch is a Microsoft tool used for build business applications.
In this article I will explain how to create and use a DropDownList in a LightSwitch application. Basically a DropDownList is a special list which shows items in the form of a list. In which we can select any item which already exists in the database.
In this article you will see, when you select a state, then a DropDownList will automatically show the cities that exist in that state.
Step 1 : First of all open Visual Studio LightSwitch->Click on create new table.
![last.png]()
Step 2 : Create three tables like customer, State, City. Which are shown below.
![image1.png]()
![image2.png]()
![image3.png]()
Step 3 : Now we will establish a relationship among these table.
Click on add relationship->Select state->Ok.
![image4.png]()
Step 4 : In the same manner as above, now process select customer then ok.
![image5.png]()
Step 5 : Right click on states table->Add query.
![image6.png]()
Step 6 : Change the query name (SortedState)->Click on sort by->Select name.
![image7.png]()
Step 7 : Now right-click on cities table->Add query.
![image8.png]()
Step 8 : Change query name (CityByState)->Click on filter->Select StateId->Click on sort->Select name.
![image9.png]()
Step 9 : Now we will add screens. Right-click on screens->Add screen.
![image10.png]()
Step 10 : Select Editable Grid Screen->Select screen data (Customers)->Ok.
![image11.png]()
Step 11 : Again add a new screen. Select new data screen->Select screen data (City)->Ok.
In the same manner, we will select the state screen data in the next step.
![image12.png]()
Step 12 : Click on Add DataItem->Click on local property->Select State(Entity)->Ok.
![image13.png]()
Step 13 : Now move SortedState to rows layout like as in the following image.
![image14.png]()
Step 14 : Again Add data item->Click on Query->Select SortedState->Ok.
![image15.png]()
Step 15 : Go to properties of SelectedState->Click on choice->Select SortedState.
![image16.png]()
Step 16 : Again add data item->Cluck on Query->Select CityByState->Ok.
![image17.png]()
Step 17 : Go to cities properties->Click on choice->Select CityByState.
![image18.png]()
Step 18 : Now click on Id properties->Write the parameter binding (SelectedState.Id).
![image19.png]()
Step 19 : Run the application (Press F5). Click on create new state to add the state in the table. In the following image you will see we enter the name of state is Bihar. In the same manner you can add more states to your table.
In the same manner you will click on Create new city to add the cities related to states.
![image20.png]()
Step 20 : When you click on editable grid screen then you can fill data like as in the following image.
![image21.png]()
Conclusion
So in this article you saw how to use and create a cascading DropDownList in LightSwitch 2011.
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