Consider a database that has the relation schema EMP (EmpId, EmpName, and DeptName). An instance of the schema EMP and a SQL query on it are given below. The output of executing the SQL query is _________.

Let us analyze the query and the data:

1. The subquery groups the relation EMP by DeptName and counts the number of employees in each department:

   • Department AA: $4$ employees (EmpId 1, 2, 3, 4)

   • Department AB: $3$ employees (EmpId 5, 6, 7)

   • Department AC: $3$ employees (EmpId 8, 9, 10)

   • Department AD: $2$ employees (EmpId 11, 12)

   • Department AE: $1$ employee (EmpId 13)

2. The subquery returns the pairs: (AA, 4), (AB, 3), (AC, 3), (AD, 2), (AE, 1).

3. The outer query computes the average of Num across all departments selected:

   $$\text{Average} = \frac{4 + 3 + 3 + 2 + 1}{5} = \frac{13}{5} = 2.6$$

Thus, the output of the query is 2.6.