What is the purpose of a subquery in SQL?
To modify data in multiple tables simultaneously.
To create a temporary table for intermediate results.
To define a new aggregate function.
To retrieve data from a table that will be used in a larger query.
In a SQL query, what does the logical operator 'AND' do?
It combines two conditions, and at least one condition must be true for the row to be included.
It combines two conditions, and both conditions must be true for the row to be included.
It sorts the results in descending order.
It negates a condition.
Which of the following is NOT a valid SQL data type?
FLOAT
BOOLEAN
VARCHAR
INTEGER
What potential issue should be considered when using correlated subqueries?
They can lead to performance issues if not used carefully.
They cannot return more than one column.
They require the use of the JOIN clause.
They cannot be used with aggregate functions.
What is the primary clause used to retrieve data from a table in SQL?
RETRIEVE
FETCH
GET
SELECT
What is the purpose of the 'LIMIT' clause in SQL?
It sorts the result set.
It filters rows based on a condition.
It restricts the number of rows returned by the query.
It groups rows with the same values.
What is the result of SELECT NOW(); in SQL?
SELECT NOW();
An error message
Current date and time
Current date
Current time
Which aggregate function would you use to find the highest value in a column?
MIN()
AVG()
MAX()
SUM()
What is the purpose of the 'OR' operator in a SQL WHERE clause?
It selects rows where both conditions are true.
It limits the number of rows returned.
It selects rows where at least one condition is true.
Which keyword is used in conjunction with the UPDATE statement to specify the conditions for updating rows?
WHERE
WHEN
IF
CONDITION