HAVING

Author: Tayeb-Ahmed-TAS

SELECT CLAUSE 2/SQL HAVING.sql

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+-- The SQL HAVING clause is used if we need to filter the result set based on aggregate functions such as MIN() and MAX(), SUM() and AVG(), and COUNT().
+-- The HAVING clause is used in combination with the GROUP BY clause to filter groups based on a specified condition.
+
+-- Syntax:
+/*
+SELECT column1, column2, aggregate_function(column3)
+FROM table_name
+WHERE condition
+GROUP BY column1, column2
+HAVING condition;
+*/
+
+-- Example: select STUDENTS with the same NAME based on their ROLL count
+
+SELECT name, COUNT(roll) AS Count
+FROM students
+GROUP BY name
+HAVING COUNT(roll) > 1;
+
+-- Example: Select the count of customer ids greater than one and their corresponding country
+
+SELECT COUNT(id), country
+FROM customers
+GROUP BY country
+HAVING COUNT(id) > 1;
+
+-- with the HAVING clause, we can use an aggregate function like SUM to calculate the sum of amounts in the order table and get the total order value of less than 5000 for each
+
+SELECT customer_id, SUM(price) AS Total
+FROM order_details
+GROUP BY customer_id
+HAVING SUM(price) < 5000;

SQL.session.sql

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+select *,
+       case
+           when age > any (select age from teachers) then 'Declined'
+           else 'Approved'
+           end as Status
+from students;