ObjectivityDB aggregation query

ObjectivityDB is a high-performance and scalable object-oriented database system. It is not a traditional relational database, but an object-oriented database. Therefore, the aggregation queries of ObjectivityDB are mainly based on the properties and relationships of objects. Specifically, ObjectivityDB supports the following aggregated queries: 1. Sum (SUM): Calculate the sum of specified attributes. For example, if there is a class named Employee with the attribute salary, we can use the following query to calculate the total salary of all employees: SELECT SUM(salary) FROM Employee 2. Count: Counts the number of objects under specified conditions. For example, assuming there is a class called Employee, we can use the following query to calculate the number of employees aged over 30: SELECT COUNT(*) FROM Employee WHERE age > 30 3. Average Value (AVG): Calculate the average value of a specified attribute. For example, if there is a class named Employee with the attribute salary, we can use the following query to calculate the average salary of all employees: SELECT AVG(salary) FROM Employee 4. Maximum value (MAX): Find the maximum value of the specified attribute. For example, if there is a class named Employee with the attribute age, we can use the following query to find the oldest employee: SELECT MAX(age) FROM Employee 5. Minimum value (MIN): Find the minimum value of the specified attribute. For example, if there is a class named Employee with the attribute age, we can use the following query to find the youngest employee: SELECT MIN(age) FROM Employee It should be noted that the aggregation query syntax of ObjectivityDB is somewhat different from traditional SQL syntax, but the concepts and effects of these query operations are similar. The above are some common examples of aggregation queries, with specific table structures and sample data that can be designed and filled in according to specific needs.