create external content type sharepoint 2010

Step 1)  Open  site in  Sharepoint Designer

Step 2) Click on External Content Type
      Change Name --> customers
         Display Name also   same
Office Item TYpe --> Generic List
Offline Sync for external list --> Enabled

Step 3)  Click on "Click here to discover external ...."

Click on "Add Connection" button --> select SQL-server from combo box

enter   database server name, db name  as shown below

Expand on Tables 

Select Customers table

Right click on Customers Table as shown below 

click on "Create All Operations"

Click on Next>> following screen will appear
In This CustomerID is  Primary of the Table Customer , so select "Show in Picker"(based on this primary key rows will be updated/deleted etc.,).

CLick Next>>  (No filter parameters)--> click FINISH

Following screen comes Click on Save button

Note: right side shows "External Content Type Operations", because user selected all operations

means get all,read one/item, insert,update,&delete

Click on Save button -->  and then click on External Content Type
following screen will appear

Now Goto  Browser  click on "Site Actions"--> "More Options" --> select "List" --> select "External List"
as shown below

                Then click on "Create" button(right side) following screen will appear
enter some name here mycustomerexternal, desc etc.,

click on External content type as shown figure,  following screen will appear

select "customer" external type  --> click on OK.  following screen will come

Click on Create button