Mysql Practice Questions
Mastering MySQL: Practice Questions
Mysql Practice Questions
MySQL practice questions are designed to help individuals improve their understanding and skills in using MySQL, a popular relational database management system. These questions cover a range of topics, such as querying databases, managing tables, and performing data manipulation tasks. By practicing these questions, individuals can reinforce their knowledge of MySQL concepts and improve their ability to write efficient and effective SQL queries. Additionally, MySQL practice questions often simulate real-world scenarios, helping individuals develop problem-solving skills that are essential for working with databases in various professional settings.
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1 - What is the difference between CHAR and VARCHAR data types in MySQL?
CHAR is a fixed length data type that stores values with a specific length, padding with spaces if necessary. VARCHAR is a variable length data type that stores values with a maximum length, saving storage space by only using the necessary amount of space.
2) How do you insert data into a table in MySQL?
You can use the INSERT INTO statement followed by the table name and column names to specify the data you want to insert. For example, INSERT INTO table_name (column1, column2) VALUES (value1, value2);
3) Explain the difference between DELETE and TRUNCATE commands in MySQL.
DELETE command is used to remove specific rows from a table based on a condition, whereas the TRUNCATE command is used to remove all rows from a table, resetting the auto increment value.
4) What is a primary key in MySQL?
A primary key is a unique identifier for each record in a table. It ensures that each row in the table is uniquely identified and helps enforce data integrity.
5) How do you retrieve data from a table in MySQL?
You can use the SELECT statement to retrieve data from a table by specifying the columns you want to select and the table you want to retrieve data from. For example, SELECT column1, column2 FROM table_name;
6) What is the difference between WHERE and HAVING clauses in MySQL?
The WHERE clause is used to filter records based on specified conditions before the data is aggregated. The HAVING clause, on the other hand, is used to filter records after the data is aggregated using GROUP BY.
7) How do you display all columns for a specific table in MySQL?
You can use the SHOW COLUMNS command followed by the table name to display all columns present in a specific table. For example, SHOW COLUMNS FROM table_name;
8) What is a foreign key in MySQL?
A foreign key is a field in a table that is a primary key in another table. It establishes a link between the two tables, ensuring referential integrity between them.
9) Explain the difference between INNER JOIN and OUTER JOIN in MySQL.
INNER JOIN returns rows when there is at least one match in both tables being compared, whereas OUTER JOIN returns all rows from both tables and fills in NULL values for missing matches.
10) What is the difference between GROUP BY and ORDER BY clauses in MySQL?
GROUP BY is used to group rows that have the same values into summary rows, while ORDER BY is used to sort the result set in ascending or descending order based on specified columns.
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