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Learning a new programming language can be daunting, especially when it comes to SQL – a language representing structured query language designed for managing data in a relational database management system (RDBMS). In this blog post, we will take a step-by-step approach to help you understand the SQL language and database management. We’ll start by explaining some fundamentals and gradually move to more complex concepts, with examples of SQL code included.
What is SQL?
SQL is a standard language for storing, manipulating, and retrieving data in databases. The beauty of SQL is that it can manage data wherever it is stored, as long as it is a relational database management system, including MySQL, Oracle, Sybase, Microsoft SQL Server, Access, etc.
SQL Basics
Let’s start by learning the basics commands in SQL: SELECT, INSERT, UPDATE, DELETE, FROM, WHERE, etc. For this example, let’s pretend we have a database named ‘Library’, including tables ‘Books’ and ‘Authors’.
SELECT Statement
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SELECT * FROM Books; |
Here * is a wildcard that stands for “everything” – this command will fetch all columns of all rows from the Books table.
INSERT Statement
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INSERT INTO Books (Book_ID, Book_Name, Author_ID) VALUES (1, 'Harry Potter', 1); |
This command will insert a new row into the Books table with the Book_ID of 1, Book_Name as ‘Harry Potter’ and Author_ID as 1.
UPDATE Statement
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UPDATE Books SET Book_Name='The Philosopher’s Stone' WHERE Book_ID=1; |
This command modifies the Book_Name for the book record with a Book_ID of 1.
DELETE Statement
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DELETE FROM Books WHERE Book_ID=1; |
This command will delete the book whose Book_ID is 1 from the Books table.
Going Further
SQL also provides powerful tools for data manipulation like JOINs, which allow us to combine rows from two or more tables based on a related column, and functions for data aggregation (SUM, AVG, etc.) and data transformation (DATE_FORMAT, CONCAT, etc.). As we progress in our SQL mastery, we will explore these more advanced features.
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/* A sample code for JOIN operation */ SELECT Authors.Author_Name, Books.Book_Name FROM Authors JOIN Books ON Authors.Author_ID = Books.Author_ID; |
Hence, learning SQL won’t only make you capable of managing and manipulating database but will also open the doors to the exciting world of data analysis and big data. Happy Learning!