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Welcome to this blog post where you get a crash course on SQL, a structured query language used for managing and manipulating databases. Regardless of the size of the database or the complexity of the operations, SQL is a powerful tool that will facilitate your interaction with databases. In this post, you’ll learn the basics to get started with SQL.
Understanding Databases and SQL
A database is an organized storage of data. These data are organized into tables, each having a unique identifier known as the Primary Key. SQL (Structured Query Language) is a language that enables you to interact with databases, enabling you to create, read, update, and delete data.
Getting Started: SELECT Statement
The SELECT statement is the cornerstone of any SQL operation. It is essentially about querying data from a database table. Below is a simple example of a SELECT statement.
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SELECT * FROM Students |
This SQL statement selects all data from the “Students” table.
WHERE Clause: Filter Data
If you only want to select data that meets a certain condition, you use the WHERE clause. The WHERE clause filters the records that satisfy the condition specified. For example:
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SELECT * FROM Students WHERE Grade = 'A' |
This SQL statement selects all students from the “Students” table where the Grade is ‘A’.
INSERT INTO Statement: Add New Data
To add new data into a database table, you use the INSERT INTO statement. Here is how to use it:
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INSERT INTO Students (StudentID, LastName, FirstName, Grade) VALUES ('101', 'Smith', 'John', 'A') |
The SQL statement above inserts a new record into the “Students” table. The new record has StudentID 101, LastName as Smith, FirstName as John, and Grade as ‘A’.
UPDATE Statement: Modify Data
The UPDATE statement allows you to modify existing data in a database table. It is used with the SET and WHERE clauses. Here’s an example:
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UPDATE Students SET Grade = 'B' WHERE StudentID = '101' |
The SQL statement above modifies the Grade for the student with StudentID 101, setting it to ‘B’.
DELETE Statement: Remove Data
The DELETE statement is used to remove existing data from a database table. It is usually used with the WHERE clause to specify the record(s) to delete. Here’s how you can use it:
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DELETE FROM Students WHERE StudentID = '101' |
The SQL statement above deletes the student with StudentID 101 from the “Students” table.
Conclusion
The SQL commands discussed in this blog post are fundamental for anyone learning database manipulation. With practice, you’ll soon be writing SQL commands like a pro!
Stay tuned for more advanced topics in SQL and happy coding!