SQL interview questions:
What does SQL stand for?
(a) Structured Language
(b) Sequential Language
(c) Standardized Query Language
(d) Systematic Question Language
What does the SQL statement “SELECT * FROM customers;” do?
(a) Deletes all records in the “customers” table
(b) Updates all records in the “customers” table
(c) Retrieves all columns and rows from the “customers” table
(d) Adds a new column to the “customers” table
What is SQL binding?
(a) A technique for securing SQL statements.
(b) A process of linking SQL queries with external data.
(c) A method for combining multiple SQL queries into one.
(d) A mechanism for associating placeholders in SQL statements with actual values.
What is the correct SQL syntax for updating the “salary” column in the “employees” table for the employee with the ID 101?
(a) MODIFY employees SET salary = 60000 WHERE employee_id = 101;
(b) UPDATE employees SET salary = 60000 WHERE id = 101;
(c) CHANGE employees SET salary = 60000 WHERE employee_id = 101;
(d) ALTER employees SET salary = 60000 WHERE id = 101;
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What is the purpose of the SQL command “UPDATE”?
(a) To insert new records into a table
(b) To delete records from a table
(c) To modify existing records in a table
(d) To create a new database
Which of the following is a correct SQL statement for selecting all columns from the ” employees ” table?
(a) SELECT ALL FROM employees;
(b) SELECT * FROM employees;
(c) RETRIEVE FROM employees ALL;
(d) PICK * FROM employees;
In prepared statements, what is the purpose of parameter binding?
(a) To execute SQL statements immediately.
(b) To link SQL statements with external files.
(c) To associate input parameters with placeholders.
(d) To compress SQL statements for faster execution.
What is the relationship between MySQL and SQL?
(a) MySQL is a type of SQL database.
(b) SQL is a programming language, and MySQL is a specific implementation of an RDBMS that uses SQL.
(c) MySQL and SQL are interchangeable terms representing the same database technology.
(d) MySQL is a more advanced version of SQL.
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Who is often considered the “father” of the relational database model and SQL?
(a) Bill Gates
(b) Steve Jobs
(c) Edgar F. Codd
(d) Larry Ellison
What does the SQL UNION operator do?
(a) Combines all columns from two tables into a single column.
(b) Concatenates the results of two SELECT queries, removing duplicate rows.
(c) Joins two tables based on specified conditions.
(d) Group rows based on a specified column.
What is the primary function of the SQL Parser in the SQL execution process?
(a) To execute SQL queries.
(b) To manage database transactions.
(c) To optimize query performance.
(d) To interpret and validate SQL statements.
Which SQL clause is used to filter the results of a query?
(a) ORDER BY
(b) GROUP BY
(c) WHERE
(d) HAVING
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Which of the following is a notable alternative to traditional SQL databases specifically designed for handling large-scale distributed data?
(a) MySQL
(b) MongoDB
(c) PostgreSQL
(d) Apache Cassandra
In which decade was SQL first developed and implemented?
(a) 1960s
(b) 1970s
(c) 1980s
(d) 1990s
What role does SQL play in the context of MySQL?
(a) SQL is an alternative to MySQL.
(b) SQL is a database system that is competing with MySQL.
(c) MySQL uses SQL as its query language for managing and manipulating data.
(d) SQL is an acronym for the MySQL database.
In a SQL UNION operation, what is the critical characteristic of the result set?
(a) It includes only distinct rows from both SELECT queries.
(b) It retains all duplicate rows from both SELECT queries.
(c) It performs an inner join on the specified columns.
(d) It orders the result set based on the specified conditions.
Which company played a vital role in the development and standardization of SQL?
(a) IBM
(b)Â Microsoft
(c) Oracle Corporation
(d)Â Amazon Inc.
What is the purpose of the SQL aggregate function “COUNT()”?
(a) To find the average value in a column
(b) To calculate the total number of rows in a table
(c) To concatenate values in a column
(d) To retrieve the highest value in a column
In SQL, what is the purpose of the USING clause in a JOIN statement?
(a) To specify the columns for joining without repeating them in the SELECT list.
(b) To filter rows based on a specified condition.
(c) To order the results of the JOIN operation.
(d) To limit the number of rows retrieved from each table.
Where did the development of SQL originate?
(a) United States
(b) United Kingdom
(c) Germany
(d) Japan
What is the purpose of the SQL Engine?
(a) To manage and store the database schema
(b) To parse and optimize SQL queries
(c) To handle user authentication and access control
(d) To provide a graphical user interface (GUI) for database interaction
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Which technology is often considered an alternative to SQL for managing unstructured data utilizing a document-oriented data model?
(a) Redis
(b) SQLite
(c) CouchDB
(d) MariaDB
Which of the following statements is true regarding the number of columns in the result set of a SQL UNION?
(a) The number of columns must be the same in both SELECT queries.
(b) The number of columns can differ in each SELECT query.
(c) The result set can include columns from only one SELECT query.
(d) The result set can include columns from multiple tables, even with different structures.
Which SQL keyword is used to retrieve data from a database table?
(a) COLLECT
(b) EXTRACT
(c) SELECT
(d) FETCH
What is the critical difference between SQL and NoSQL databases?
(a) SQL databases use a schema, while NoSQL databases are schema-less.
(b) NoSQL databases are limited to small datasets, while SQL databases handle large datasets.
(c) SQL databases are only suitable for web development, while NoSQL databases are versatile.
(d) SQL databases are open-source, while NoSQL databases are proprietary.
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What is the role of the “Transaction Manager” in SQL databases?
(a) To interpret and execute SQL commands.
(b) To manage user authentication and access control.
(c) To optimize the performance of SQL queries.
(d) To ensure the consistency and integrity of database transactions.
What is the correct syntax for updating data in an SQL table?
(a) MODIFY table SET column = value WHERE condition;
(b) CHANGE table SET column = value WHERE condition;
(c) UPDATE table SET column = value WHERE condition;
(d) ALTER table SET column = value WHERE condition;
What does the term “ETL” stand for in SQL integration?
(a) Extract, Transform, Load
(b) Encrypt, Transfer, Log
(c) Execute, Test, Learn
(d) Export, Track, Log
Which SQL statement is used to filter the results of a query?
(a) ORDER BY
(b) LIMIT
(c) WHERE
(d) GROUP BY
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Which is a common approach to real-time data integration in SQL?
(a) Batch processing
(b) Incremental loading
(c) Stream processing
(d) Snapshot replication
How can SQL injection occur?
(a) By using complex and lengthy SQL queries.
(b) By modifying the database schema.
(c) By injecting malicious SQL code through user inputs.
(d) By encrypting SQL statements.
Which SQL keyword is used to eliminate duplicate rows from the results of a query?
(a) UNIQUE
(b) DISTINCT
(c) NO_DUPLICATES
(d) SINGLE
In the context of SQL development, what is the purpose of the term “Normalization”?
(a) Enhancing database security
(b) Reducing redundancy in data
(c) Accelerating query performance
(d) Creating database backups
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What is the role of the SQL Parser in the SQL execution process?
(a) It stores data on a disk.
(b) It manages user authentication.
(c) It interprets and validates SQL statements.
(d) It optimizes the performance of SQL queries.
What is the primary purpose of an SQL database?
(a) To store and manage data
(b) To execute web-based scripts
(c) To design user interfaces
(d) To create graphical elements
In SQL integration, what is the purpose of the “Transform” phase in the ETL process?
(a) Extracting data from source systems.
(b) Loading data into the target database.
(c) Modifying and cleaning data for consistency.
(d) Managing the scheduling of data integration tasks.
Which SQL extension is commonly used to integrate machine learning capabilities into SQL databases?
(a) SQL/ML
(b) ML/SQL
(c) PL/SQL
(d) SQLite/ML
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What is the default port number for MySQL connections?
(a) 1433
(b) 3306
(c) 5432
(d) 1521
Which SQL command is used to create a new database?
(a) MAKE DATABASE
(b) CREATE DB
(c) NEW DATABASE
(d) CREATE DATABASE
What does the SQL term “primary key” refer to?
(a) A unique identifier for a table, ensuring each row is distinct.
(b) A reserved keyword for executing administrative tasks.
(c) An aggregate function for calculating the average value in a column.
(d) A command for creating new tables in a database.
Which SQL statement is used to insert a new record into a table named “students” with specified values for the columns “name” and “age”?
(a) ADD INTO students (name, age) VALUES (‘John’, 21);
(b) INSERT INTO students (name, age) VALUES (‘John’, 21);
(c) CREATE INTO students (name, age) VALUES (‘John’, 21);
(d) APPEND INTO students (name, age) VALUES (‘John’, 21);
What does the term “ACID” stand for in the context of SQL transactions?
(a) Atomicity, Concurrency, Isolation, Durability
(b) Association, Coordination, Integration, Dependability
(c) Analysis, Compilation, Implementation, Deployment
(d) Authentication, Configuration, Initialization, Delegation
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Which statement best describes the data model of SQL databases compared to NoSQL databases?
(a) SQL databases use a flexible, document-based model.
(b) SQL databases are primarily based on key-value pairs.
(c) SQL databases follow a rigid, structured, tabular model.
(d) NoSQL databases provide a standardized table structure.
What does the SQL acronym “DDL” stand for?
(a) Data Definition Language
(b) Data Display Language
(c) Database Design Language
(d) Data Deletion Language
How does SQL contribute to content management systems?
(a) By designing user interfaces for CMS.
(b) By encrypting sensitive content in CMS.
(c) By providing a standardized language for querying and managing data in CMS databases.
(d) By optimizing the performance of CMS websites.
What is the purpose of the “WHERE” clause in a SELECT statement?
(a) To specify the columns to be retrieved.
(b) To group rows based on a specified column.
(c) To filter rows based on a specified condition.
(d) To join multiple tables in a query.
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Which of the following is a common type of NoSQL database that uses a document-oriented data model?
(a) Cassandra
(b) Redis
(c) MongoDB
(d) Neo4j
What is the purpose of the SQL statement “DELETE FROM table_name WHERE condition;”?
(a) To remove a database
(b) To delete all records from a table
(c) To add new records to a table
(d) To modify existing records in a table
