#1
Which keyword is used to create a view in SQL?
CREATE VIEW
ExplanationDefines a virtual table based on the result of a SELECT statement.
#2
What is the primary purpose of SQL query optimization?
To minimize the query execution time
ExplanationEnhances query performance by reducing resource consumption and execution time.
#3
Which SQL function is used to find the maximum value in a column?
MAX()
ExplanationReturns the maximum value in a specified column.
#4
What is the purpose of a SQL index?
To improve the performance of queries
ExplanationSpeeds up data retrieval by providing quick access to rows in a table.
#5
Which SQL statement is used to update data in a database?
UPDATE
ExplanationModifies existing data in a table based on specified conditions.
#6
Which SQL keyword is used to specify the order of the result set?
ORDER BY
ExplanationSorts the result set based on specified column(s) in ascending or descending order.
#7
In SQL, which type of join returns all rows from both tables, joining records where available?
OUTER JOIN
ExplanationRetrieves matching records and includes non-matching rows from both tables.
#8
What is a correlated subquery in SQL?
A subquery that uses values from the outer query
ExplanationExecutes a subquery for each row processed by the outer query.
#9
Which index type in SQL can speed up SELECT queries but may slow down data modification operations?
Non-clustered index
ExplanationImproves read performance by storing index keys separate from the actual data.
#10
What does ACID stand for in the context of database transactions?
Atomicity, Consistency, Isolation, Durability
ExplanationDefines properties ensuring reliable and consistent transaction processing.
#11
Which SQL clause is used to limit the number of rows returned by a query?
LIMIT
ExplanationRestricts the number of rows returned in the result set.
#12
What is SQL injection?
A technique to manipulate a database by injecting malicious SQL code
ExplanationExploits vulnerabilities by injecting malicious SQL code to gain unauthorized access.
#13
In SQL, what is the purpose of the HAVING clause?
To specify conditions on groups
ExplanationFilters groups based on specified conditions after the GROUP BY clause.
#14
What is a scalar subquery in SQL?
A subquery that returns a single value
ExplanationReturns a single value as a result.
#15
What is a derived table in SQL?
A table created temporarily within the scope of a query
ExplanationExists only for the duration of the query execution.