For an instructor lead, in-depth look at learning SQL click below.
Welcome to SQL 101! Structured Query Language (SQL) is a powerful tool used for interacting with databases. It allows us to create, manipulate, and query data in a relational database. Regardless of the size of the database or the complexity of the operations, the SQL language remains foundational to the field of data analytics.
What is SQL?
SQL is a standardized programming language specifically used for managing data held in relational database management systems. With SQL, you can query your data, make updates, and perform intricate functions with just a few commands. It is widely used due to its simplicity and high efficiency.
Getting Started with SQL
Before diving into SQL commands, let’s take a look at what a typical SQL operation looks like. The following is a simple SQL SELECT statement:
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SELECT * FROM Customers |
This command selects all the records in the ‘Customers’ table. In SQL, the asterisk (*) is used as a wildcard character that stands for ‘all’.
SQL Basic Commands
CREATE TABLE
The CREATE TABLE statement is used to create a new table in a database:
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CREATE TABLE Employees ( EmployeeId INT, FirstName VARCHAR(255), LastName VARCHAR(255), Position VARCHAR(255), Salary INT) |
This code creates a new table called ‘Employees’ with the columns ‘EmployeeId’, ‘FirstName’, ‘LastName’, ‘Position’, and ‘Salary’.
INSERT INTO
Once you have a table, you can insert data using the INSERT INTO statement:
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INSERT INTO Employees (EmployeeId, FirstName, LastName, Position, Salary) VALUES (1, 'John', 'Doe', 'Manager', 50000) |
This commands add a record to the ‘Employees’ table with values specified for each column.
DELETE
To delete a record from a table, you can use the DELETE statement combined with a WHERE clause to specify the record:
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DELETE FROM Customers WHERE CustomerName='John' |
This command would delete all records from the ‘Customers’ table where the ‘CustomerName’ is ‘John’.
Conclusion
SQL is a powerful, indispensable tool for data management and analysis. By starting with these fundamental commands, you’re on your way to mastering SQL. In the upcoming parts of this tutorial, we will be delving into more advanced topics such as joins, functions, subqueries, and more. Stay tuned!