SciCoNet
SciCoNet
helpdelete

Introduction to SQL

SQL stands for Structured Query Language. It is a standard language used for managing relational databases. SQL allows you to access and manipulate the data stored in a relational database.

SQL is used by many companies to manage their data, including Google, Facebook, and Amazon. It is a powerful tool that allows you to retrieve, insert, update, and delete data from a database.

Basic SQL Commands

There are several basic SQL commands that you need to know in order to work with a database:

  • SELECT: used to retrieve data from a database
  • INSERT: used to insert new data into a database
  • UPDATE: used to update existing data in a database
  • DELETE: used to delete data from a database

SELECT

The SELECT command is used to retrieve data from a database. It allows you to select specific columns from a table, or retrieve all columns using the wildcard *.

Here is an example of a SELECT statement:

SELECT name, age FROM users;

This statement selects the name and age columns from the users table.

INSERT

The INSERT command is used to insert new data into a database. You need to specify the table and the columns you want to insert data into, as well as the values you want to insert.

Here is an example of an INSERT statement:

INSERT INTO users (name, age) VALUES ('John Doe', 30);

This statement inserts a new row into the users table with the name "John Doe" and the age 30.

UPDATE

The UPDATE command is used to update existing data in a database. You need to specify the table and the columns you want to update, as well as the new values you want to set.

Here is an example of an UPDATE statement:

UPDATE users SET age = 31 WHERE name = 'John Doe';

This statement updates the age column of the row where the name is "John Doe" to 31.

DELETE

The DELETE command is used to delete data from a database. You need to specify the table and the condition that must be met for a row to be deleted.

Here is an example of a DELETE statement:

DELETE FROM users WHERE name = 'John Doe';

This statement deletes all rows from the users table where the name is "John Doe".

Conclusion

SQL is a powerful tool that allows you to manage relational databases. It is used by many companies to store and retrieve data. By learning the basic SQL commands, you can start working with databases and manipulating data.

SQL[JA]