History of SQL
SQL databases have been used for decades and continue to be widely used to this day. In 1969 IBM researcher Edgar “Ted” Codd defined the relational database model, which became the basis for developing the SQL model. The model is built on keys being associated with various data.
What is SQL?
The term SQL stands for “Structured Query Language”, it is a standard programming language that is used to communicate with databases. SQL is a lightweight, declarative language that does a lot of heavy lifting for the relational database, acting as a database’s version of a server-side script. The amount of data that we produce on a daily basis is massive and that's where databases come in handy. SQL is made up of rows and columns stored in the form of tables. Each row in a table is known as a record and the column is a field that describes the row.
Advantages of SQL
SQL is widely used because of the advantages that it offers:
- Allows users to access data in the relational database management systems.
- Allows users to describe the data.
- Allows users to define the data in a database and manipulate that data.
- Allows embedding within other languages using SQL modules, libraries & pre-compilers.
- Allows users to create and drop databases and tables.
- Allows users to create a view, stored procedure, functions in a database.
- Allows users to set permissions on tables, procedures, and views.
RBDMS stands for Relational Database Management System and is the basis for SQL. It takes into account the relationship between tables by implementing the use of primary keys, foreign keys, and indexes. It enables users to define, create, maintain, and control access to a database. Some examples of various RBDMS are MySQL, SQLite, SQL Server Express, and PostgreSQL.
Here we’ll go over the four most commonly used SQL statements along with examples. These four statements are foundation operations that every developer needs to understand in order to write proper queries.
SELECT — this statement lets you retrieve data from the database, it gives you the ability to choose from multiple tables and specify with the column you want to extract data from.
SELECT exampleColumn, exampleColumn2
INSERT - this statement allows you to insert new rows into a table.
INSERT INTO exampleTable (newRow)
UPDATE- allows you to update one or more records in the database.
SET newRow = ‘Updated Value’;
DELETE- allows you to delete specified rows from a table
DELETE FROM exampleTable
WHERE newRow = “newValue “ ;