MySQL Quiz – Test Your Skills 35 Questions + Answers (35)

A A. Database Management System B B. Relational Management System C C. Relation Database Management System D D. Relational Database Management System

A A. Swedish company B B. American company C C. Norway company D D. Japanse company

A A. on 21 May 1995 B B. on 22 May 1995 C C. on 23 May 1995 D D. on 24 May 1995

A A. Microsoft B B. Oracle C C. Apple D D. MySQL

A A. June 9, 2011 B B. July 9, 2011 C C .Sept 9, 2011 D D. Oct 9, 2011

A A. GET B B. FETCH C C. SELECT D D. RETRIEVE

A A. No difference — they are interchangeable B B. WHERE filters individual rows BEFORE grouping; HAVING filters groups AFTER GROUP BY C C. HAVING works only on indexed columns; WHERE works on all columns D D. WHERE is for JOINs; HAVING is for subqueries

A A. Returns all rows from the left table even if no match exists in the right B B. Returns only the rows where there is a match in BOTH tables C C. Combines all rows from both tables regardless of matching D D. Returns rows only from the right table

A A. The first column in any table B B. A unique identifier for each row — cannot be NULL and must be unique across the table C C. A foreign key that references another table D D. An index that allows duplicate values

A A. No difference — they store the same data B B. CHAR always uses fixed 10-byte storage; VARCHAR uses only as many bytes as the actual content plus 1-2 bytes overhead C C. VARCHAR is for numbers; CHAR is for strings D D. CHAR stores Unicode; VARCHAR stores ASCII

A A. Automatically updates a column value on every UPDATE B B. Automatically assigns a unique incrementing integer value to a column on each INSERT C C. Creates an automatic index on the column D D. Prevents the column from being manually updated

A A. To enforce data uniqueness only B B. To speed up data retrieval operations at the cost of additional storage and slower writes C C. To encrypt table data for security D D. To create a backup copy of the table

A A. Shows the full table structure B B. Analyzes and displays how MySQL executes a SELECT query — indexes used, rows scanned, join types C C. Generates query documentation D D. Explains foreign key relationships

A A. They all do the same thing — remove data permanently B B. DELETE removes specific rows (logged, can WHERE); TRUNCATE removes all rows fast (not fully logged); DROP removes the entire table including structure C C. DROP is the safest; DELETE is the most dangerous D D. TRUNCATE can be rolled back; DELETE cannot

A A. Sorts query results in ascending order B B. Groups rows with the same values in specified columns and allows aggregate functions (COUNT, SUM, AVG) per group C C. Combines two tables based on matching columns D D. Limits the number of rows returned

A A. A key from an external database B B. A column (or set of columns) that references the PRIMARY KEY of another table, enforcing referential integrity C C. An encrypted primary key D D. An index on a non-primary column

A A. A single SELECT query that reads multiple tables at once B B. A sequence of SQL operations treated as a single atomic unit — either all succeed (COMMIT) or all fail (ROLLBACK) C C. A scheduled automated query D D. A query that runs in a separate database thread

A A. An encryption algorithm used by MySQL B B. Atomicity, Consistency, Isolation, Durability — four properties that guarantee database transaction reliability C C. A query optimization technique D D. An indexing method for faster lookups

A A. Selects only the first unique row from each table B B. Returns only unique (non-duplicate) rows from the result set C C. Selects rows with distinct primary keys only D D. Selects rows with no NULL values

A A. No difference — they are identical B B. UNION removes duplicate rows from combined results; UNION ALL includes all rows including duplicates and is faster C C. UNION ALL removes duplicates; UNION keeps all rows D D. UNION works across databases; UNION ALL works within one database

A A. Limits the number of columns returned B B. Restricts the number of rows returned by a query, often used for pagination C C. Limits the query execution time D D. Sets a maximum value for a column

A A. An empty string or zero value B B. The absence of a value — use IS NULL or IS NOT NULL to check (not = NULL) C C. A default placeholder replaced automatically by MySQL D D. A value of exactly 0

A A. A saved SELECT query that runs automatically on INSERT B B. A reusable block of SQL code stored in the database that can accept parameters and be called by name C C. A type of database trigger D D. An encrypted query saved in a file

A A. Deletes the parent table when the child is deleted B B. Automatically deletes all child rows when the referenced parent row is deleted C C. Prevents deletion of a parent row if child rows exist D D. Updates the foreign key to NULL when the parent is deleted

A A. InnoDB is for read-only tables; MyISAM is for write-heavy tables B B. InnoDB supports ACID transactions, foreign keys, and row-level locking; MyISAM is faster for reads but lacks transactions and uses table-level locking C C. They are identical in functionality; InnoDB just uses more memory D D. MyISAM supports JSON columns; InnoDB does not

A A. A backup copy of a table stored separately B B. A virtual table defined by a SELECT query — simplifies complex queries and can enforce access control C C. A type of index that speeds up complex JOINs D D. A snapshot of table data taken at a specific time

A A. Combines (concatenates) two strings together B B. Returns the first non-NULL value from a list of arguments C C. Counts non-NULL values in a column D D. Converts NULL to an empty string automatically

A A. An index that combines data from two different tables B B. An index on multiple columns — efficient when queries filter on all or the leading columns of the index C C. An index that compresses data to save space D D. A full-text index for searching multiple columns simultaneously

A A. An index that stores the full content of the table for backup purposes B B. Natural language and boolean text searching on text columns — much faster and smarter than LIKE '%word%' C C. An index that allows full column encryption D D. A type of index that indexes NULL values

A A. Shows all stored procedures and functions B B. Displays all currently running queries and connections — useful for finding slow or stuck queries C C. Lists all database users and their permissions D D. Shows the query execution history

A A. Converting all column names to lowercase B B. Organizing database tables to reduce data redundancy and improve data integrity through a series of normal forms (1NF, 2NF, 3NF) C C. Optimizing queries by rewriting them in normal form D D. Backing up the database in a standardized format

A A. Switches between different database connections B B. Implements conditional logic inside SELECT queries — similar to IF/ELSE C C. Changes column data types dynamically D D. Creates a switch-case stored procedure

A A. A secondary database used for read operations B B. A query nested inside another query — can be scalar (single value), row, column, or table subqueries C C. A MySQL procedure that calls another procedure D D. A query that runs on a slave replication server

A A. Copying SQL files from one folder to another B B. Asynchronously copying data from a master server to one or more replica servers for redundancy, scaling reads, and backups C C. Creating table copies within the same database D D. An automatic data deduplication feature

A A. Returns the total count of rows in the table B B. Assigns a unique sequential integer to each row within a partition of a result set, starting at 1 C C. Returns the row number of the PRIMARY KEY column D D. Creates an auto-incrementing row ID for temporary tables