SQL concepts you must read before going for a data scientist interview
Data science is one of the most in-demand professions, and everyone has been trying to get a job in this field. But before you go for the interview, it's always good to have an idea about the concept and things related to data science. So here, we will discuss some data science interview questions.
What is the difference between MySQL and SQL?
SQL, or Structured Query Language, is used to create and manipulate databases. It can be considered a programming language that allows you to write queries and get results from them.
MySQL is an open-source database management system. It's an RDBMS (Relational Database Management System), which stores data in tables rather than files or memory buffers like other DBMSs do.
What is a Database Management System (DBMS)?
A database management system is a program that allows you to store, organize and retrieve data on a computer. It's a collection of programs that manages the database.
SQL is a database management language. It creates, modifies, and queries databases. It is a declarative language that allows you to create and manipulate tables in your database using commands like CREATE, INSERT, and UPDATE.
What is an Index?
It is a data structure that makes finding information faster. The index stores the same information as the original table but can be searched much faster because of its optimized system.
What is a Foreign Key? Demonstrate How to Implement it
It is a set of columns that refer to a primary key in another table. It enforces referential integrity and ensures that data from the parent table is related to the child table.
Assume you have a database with one customer row per person and their orders (a list of products bought by each customer). You want to add some additional information about each order, such as when it gets placed, how much it costs, etc., which means you need another table called "Orders" with four fields - date_of_order (date), product_name(product), quantity(quantity) and price($).
What is the Difference Between DML and DDL?
Data Definition Language (DDL) is a programming language that enables users to define database data structures. It also allows you to create new tables or insert data into existing ones.
Data Manipulation Language (DML) is another programming language used by database administrators and developers who work on relational databases like Oracle or MySQL, which store information in tables with columns and rows.
The difference lies in how they work together. While DBAs use DMLs for manipulating your database's contents using SQL statements, developers use DDLs for creating/updating them using SQL statements too!
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