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Welcome to SQL 101. In this guide, we will illuminate the basics of SQL, a standard language for managing data in databases. This comprehensive guide is ideal for beginners who are looking to understand and grasp the fundamental aspects of SQL.
What is SQL?
SQL, or Structured Query Language, is a programming language used to communicate with and manipulate databases. It is particularly effective when handling structured data, i.e., data incorporated into a database in a systematic or organized manner.
Understanding SQL Basics
There are several imperative SQL operations you must understand, these are:
1. Create Table
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CREATE TABLE Customers( ID INT PRIMARY KEY NOT NULL, NAME TEXT NOT NULL, AGE INT NOT NULL, ADDRESS CHAR(50), SALARY REAL ); |
This command is used to create a new table in the database. In the example above, we are creating a new table named ‘Customers’ with five columns: ID, Name, Age, Address, and Salary.
2. Insert Into
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INSERT INTO Customers (ID,NAME,AGE,ADDRESS,SALARY) VALUES (1, 'John', 32, '10 Downing St London', 30000.00 ); |
The INSERT INTO statement is used to insert a new row into a table. Here, we are adding a new customer to our ‘Customers’ table
3. Select
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SELECT * FROM Customers; |
The SELECT statement is used to select data from a database. The data returned is stored in a result table, called the result-set. The asterisk (*) is used to select all columns.
4. Update
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UPDATE Customers SET ADDRESS = '15 Downing St London', SALARY = 35000.00 WHERE ID = 1; |
UPDATE is used to modify the existing records in a table. This statement updates the address and salary of the customer with the ID 1.
5. Delete
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DELETE FROM Customers WHERE ID = 1; |
DELETE is used to delete existing records in a table. This statement would delete the customer with ID number 1 from the Customers table.
Conclusion
There’s a lot more to SQL than what’s covered in this guide. However, mastering these basics is a giant step towards becoming proficient in the language, and will serve as a sturdy foundation for more advanced concepts.