18 Questions
What must be included in the GROUP BY clause in SQL statements when using expressions that are not encapsulated within the AVG function?
Only the column_name used for counting
Which clause in SQL is optional but allows for specifying conditions that must be met for records to be selected?
WHERE
What is the default sorting order for the result set when using the ORDER BY clause without specifying ASC or DESC?
Ascending order
Which type of values are NOT counted by the COUNT function in SQL?
Only non-NULL values
In SQL, what happens if more than one expression is provided for sorting in the ORDER BY clause?
The values are comma separated
What is necessary when using the COUNT function with expressions that are NOT NULL values?
Ensuring the expression is NOT NULL
What does the COUNT function do in SQL?
Returns the number of employees that make over $50,000 for each dept_id
When using the COUNT function in SQL, why is the GROUP BY clause necessary?
To group the results based on a specified column or columns
In SQL, what does the DISTINCT keyword do when used with the COUNT function?
Removes duplicate values before counting
Which function in SQL is used to return the maximum value of an expression?
MAX
What is the purpose of the WHERE clause in SQL?
To filter rows based on a specific condition
When would you use the GROUP BY clause in SQL?
To apply aggregate functions like COUNT per group
What is the purpose of the SQL GROUP BY clause?
To organize data across multiple records and group results by one or more columns
When using the COUNT function in SQL, what happens if the column being counted is not listed in the GROUP BY clause?
An error occurs
How can the WHERE clause be used in SQL?
To filter rows based on specified conditions
What role does the AVG function play in SQL?
It calculates the average value of a column
In SQL, why is it important to include all non-aggregated columns from the SELECT statement in the GROUP BY clause?
To ensure proper syntax and functioning of the query
Which SQL function is commonly used to count the number of occurrences of a specified column?
COUNT
Test your knowledge on the SQL GROUP BY clause that is used to group rows that have the same values into summary rows. This quiz covers concepts such as using aggregate functions like SUM, COUNT, or AVG with GROUP BY clause.
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