SQL

SQL (Structured Query Language) is a standard computer language for relational database management and data manipulation. SQL is used to query, insert, update, and delete data in relational databases. 

 SQL is a standard database language that is supported by all major relational database management systems (RDBMSs). SQL is an ANSI (American National Standards Institute) standard. The SQL standard is maintained by the ISO/IEC JTC 1/SC 32 working group. 

 The most recent version of the SQL standard is SQL:2016. SQL is a declarative language, meaning that the programmer specifies what data to retrieve, rather than how to retrieve it. This makes SQL easy to learn and use. 

 SQL is a powerful language that can be used for a wide variety of tasks, such as retrieving data from databases, inserting data into databases, updating data in databases, and deleting data from databases. SQL can be used to query databases for specific information, such as the names of all the employees in a company, the total sales for a particular product, or the total number of orders placed by a customer. SQL can also be used to insert data into databases, update data in databases, and delete data from databases. SQL is a very versatile language and can be used for a wide variety of tasks. 

SQL query execution order generally goes as follows: 

1. Parse the query 

2. Optimize the query 

3. Execute the query 

1. Parse the query: The SQL query is parsed, or checked for proper syntax. This is the first step in query execution. 

2. Optimize the query: The SQL query is optimized, or planned, for execution. This step can involve many different optimizations, such as choosing the best indexes to use, selecting the most efficient algorithms, and more. 

3. Execute the query: The SQL query is executed, or run, on the database. This step retrieves the requested data from the database and returns it to the user.

Websites to learn SQL Queries 

1. SQLBolt - https://sqlbolt.com/ 

2. W3Schools - https://www.w3schools.com/sql/ 

3. Codecademy - https://www.codecademy.com/learn/learn-sql 

4. SQLZOO - https://sqlzoo.net/ 

5. Mode Analytics - https://community.modeanalytics.com/sql/tutorial/introduction-to-sql/ 

6. DataCamp - https://www.datacamp.com/courses/introduction-to-sql