For an instructor lead, in-depth look at learning SQL click below.
Welcome aspiring SQL enthusiasts! SQL, or Structured Query Language, is a universal language for managing data held in relational database management systems. This open-door tool can be learned by anyone interested in organizing, managing, and retrieving data. Today, we’ll be looking into the fundamentals of SQL and sharing resources and examples to help beginners hit the ground running.
SQL Basics
The most basic operation in SQL is fetching data from a database, which is done using the SELECT statement. Here’s a typical example:
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SELECT * FROM Employees; |
In this SQL statement, “*” means “all columns”, and “Employees” is the name of the table from which we want to fetch data. It returns a table-like dataset including all the information stored in the “Employees” table.
SQL Tables
Creating tables in SQL is easy. The following example generates a “Customers” table:
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CREATE TABLE Customers ( CustomerID int, CustomerName varchar(255), ContactName varchar(255), Country varchar(255), ); |
This creates a new table in the database, which includes four columns, namely CustomerID, CustomerName, ContactName, and Country. Each column has a specific datatype which defines the kind of data it can store.
Inserting Data
Here’s an example of how to insert data into the “Customers” table:
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INSERT INTO Customers (CustomerID, CustomerName, ContactName, Country) VALUES (1, 'John Smith', 'JSmith', 'USA'); |
Updating Data
Already stored data can be modified using the UPDATE statement. Here’s how to change John Smith’s contact name:
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UPDATE Customers SET ContactName='John.Smith' WHERE CustomerID=1; |
Deleting Data
To delete data, use the DELETE statement. For instance, if we want to remove John Smith from our records:
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DELETE FROM Customers WHERE CustomerID=1; |
Essential Resources for Learning SQL
There are many great resources for learning SQL. Here are a few of my favorites:
Immerse yourself in these resources and practice regularly on a database system of your choice. Remember, hands-on experience is paramount when it comes to learning SQL. Have fun exploring!