SQL Exercises: Find number of customers have listed their names
SQL Aggregate Functions: Exercise-4 with Solution
From the following table, write a SQL query to count the number of customers. Return number of customers.
Sample table: customer
SELECT COUNT(*) FROM customer;
Output of the Query:
The said SQL query that retrieve the total number of rows in the 'customer' table. The "SELECT COUNT(*)" statement specifies that the number of rows in the table should be counted. The "(*)" is a wildcard that counts all rows, regardless of the specific columns and their values.
The result of this query will be a single value that represents the total number of rows in the 'customer' table.
Relational Algebra Expression:
Relational Algebra Tree:
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Previous SQL Exercise:Find the number of salesmen for each customer.
Next SQL Exercise: How many customers get a grade for their performance.
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