How to use pass variables in Execute SQL task

Here is a post where I actually did to pass variables into SQL query using Execute SQL task.
Here is my condition that I need to count number of rows in one table and need to pass this count value into a variable and then  using that variable I need to insert into a table.

For this Purpose let me take a table named 'Dim' under Database 'test' and similarly I will take one more table called 'fact' under database name 'test' again.

Using SSIS, I will take Execute SQL task on workspace, In fact two as we need two executions has to be done.
Let us create a variable as we discussed earlier of this task purpose and I'm creating a variable called "testing".

Right click on first Execute SQL task, go for edit and here, I will configure as shown in snippet below.

Here importantly we need to set ResultSet as Single row as ResultSet option will activate Result Set tab of Execute process task where we can assign variables and expressions.
There are many other options in ResultSet and I'm concentrating only on Single Row for now.

Note: Whatever query we will write, The result will be passed to Result Set tab of Execute SQL task.

 

Here I'm assigning variable "Testing" I created earlier. This means, whatever values are obtained from SQL statement, That value will be assigned to variable User::Testing.

Now again we need to take one more Execute SQL task for 2nd condition purpose (Inserting the value into table using variable)
Again, right click and go for Edit and continue as shown in snippet.

Here there is no need of giving ResultSet as we know we are not passing result of query in this Execute SQL task to any variable rather, we are getting values from variable to SQL statement.

Now go for Build Query and then

Query will be built automatically. then go for Run.
 (Note: Observe that ? symbol. Instead of this ? symbol we can give @testing and we need to change as @testing even at parameter mapping of This Execute SQL task. I will show you with snippet where to change)

after Run, we have to get this.

Now we will cancel here and give Ok to remaining windows been opened. (Not giving ok at this window will insert a value into table which may lead to duplicates get inserted)

Next go to Parameter Mapping tab

Here we need to give variable value we created.
Now remember, I mentioned earlier we also can give @testing and this is given at parameter name. (second circle)

Here we have given 0, because, We have only one parameter.
If we have created two parameter, Then based on priority, we need to give values like 0,1, etc
(suppose you are having two parameters then 0 or1 )

Now Run the package and we can see the result at destination table FACT