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Welcome to our SQL tutorial where we will delve into the basics of SQL, or Structured Query Language. SQL is the language that we use to interact with databases to create, read, update, and delete data. It’s an essential tool for any aspiring data analyst, web developer, or database administrator.
Introduction to SQL
SQL is a language designed to manipulate and manage data stored in relational databases. It allows programmers to create databases, tables, views, stored procedures, and more. Additionally, SQL provides the means to query the data, meaning retrieve, insert, update, or delete it.
Writing a basic SQL Query
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SELECT * FROM Customers; |
This fundamental query is telling the database to return (“select”) all the fields (*) from the table called Customers.
Creating a table
When creating a table, we need to define it with a name and give each column in it a name and data type.
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CREATE TABLE Employees ( ID int, Name varchar(255), Age int, Address varchar(255), Salary decimal(18, 2) ); |
Inserting Data
To insert data into the table, we use the INSERT command:
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INSERT INTO Employees (ID, Name, Age, Address, Salary) VALUES (1, 'John Doe', 30, '123 Main Street', 50000.00); |
Updating Data
To update records in a table, we use the UPDATE command:
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UPDATE Employees SET Address = '456 Elm Street', Salary = 75000.00 WHERE ID = 1; |
This statement says to update the Employees table, set the Address to ‘456 Elm Street’ and the Salary to 75000.00 where the ID is 1.
Conclusion
These examples provide a brief overview of SQL basics and common commands. SQL is a versatile tool, which you can become comfortable with through continued practice. Stay tuned to our blog for more advanced SQL topics and happy querying!