Consider the following database table named $water\_schemes$ : The number of tuples returned by the following SQL query is _______ .with total(name, capacity) as select district_name, sum(capacity) from water_schemes group by district_name with total_avg(capacity) as select avg(capacity) from total select name from total, total_avg where total.capacity ≥ total_avg.capacity

To determine the number of tuples returned by the query, let us evaluate the query step by step:

1. First CTE (total): Groups by district_name and calculates the total capacity for each district:

   • Ajmer: $20$

   • Bikaner: $10 + 10 + 20 = 40$

   • Churu: $10 + 20 = 30$

   • Dungargarh: $10$

2. Second CTE (total_avg): Calculates the average of the aggregated capacities in total:

   $$\text{Average capacity} = \frac{20 + 40 + 30 + 10}{4} = \frac{100}{4} = 25$$

3. Main Query: Selects the name from total where total.capacity $\ge 25$:

   • Bikaner ($40 \ge 25$): satisfies the condition

   • Churu ($30 \ge 25$): satisfies the condition

   • Ajmer ($20 < 25$): does not satisfy

   • Dungargarh ($10 < 25$): does not satisfy

Thus, 2 tuples (Bikaner, Churu) are returned.