SQL Exercises: Find the number of salesmen for each customer
SQL Aggregate Functions: Exercise-3 with Solution
From the following table, write a SQL query that counts the number of unique salespeople. Return number of salespeople.
Sample table: orders
SELECT COUNT (DISTINCT salesman_id) FROM orders;
Output of the Query:
The given SQL query that retrieve the number of unique values in the "salesman_id" column from the 'orders' table. The "SELECT COUNT (DISTINCT salesman_id)" statement specifies that the number of unique values in the "salesman_id" column should be counted.
By using the keyword "DISTINCT", it is ensured that only unique values will be counted and duplicate values will not be added to the final result in any way.
The result of this query will be a single value that represents the number of unique values in the "salesman_id" column in the 'orders' table.
Relational Algebra Expression:
Relational Algebra Tree:
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Previous SQL Exercise: Find the average purchase amount of all orders.
Next SQL Exercise: Find number of customers have listed their names.
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SQL: Tips of the Day
What is the best way to paginate results in SQL Server?
SELECT * FROM ( SELECT ROW_NUMBER() OVER ( ORDER BY OrderDate ) AS RowNum, * FROM Orders WHERE OrderDate >= '1980-01-01' ) AS RowConstrainedResult WHERE RowNum >= 1 AND RowNum < 20 ORDER BY RowNum
Database: SQL Server
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