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If you aim of becoming the Data Scientist or Data Analyst, then it is mandatory and necessary to have a good knowledge of SQL which is Structured Query Language. For the beginners, the step by step guide will help in understanding the SQL easily. SQL is a simple language; it is not necessary to be from an engineering background to learn it. If you have a passion for learning a database design language, then SQL is the stop which you can easily be nailed in a few days of practice. The guide is based on practical knowledge of SQL and has used the easy and basic methods of explaining the programming of SQL.
Understanding what SQL is
The Structured Query Language is used to establish communication with other relational databases. SQL represents the data in the form 2-Dimension format table with rows and columns. It is built structurally and transparently. Few things need to be learned at the beginning of the SQL:
- Focusing on the performance of the SQL which processed an approx. Of 10 million rows set pretty fast.
- Another point to be a focus on is how your data can be accessed. Through SQL queries, you can learn how to access a data.
The benefits of SQL can be that you can easily start joining the tables and can automate them. The concept of reusing the code can easily be worked out here as more efficiently. SQL can be used for analyzing data for tasks like joining a set of data, simple stats, aggregation of data, etc. And timely, you will grow on performing data analysis on bigger sets of data. For more information, you can subscribe to RemoteDBA.comand get guidance from top experts.
Installing SQL at your System
For installing the SQL in your system environment, you require major things like:
- Server with Terminal accessibility
- SQL should be there on the server
- Your computer must be integrated with SQL Workbench
Don't miss out on anything from above. Otherwise, SQL will not get properly installed.
Accessing SQL database from the command line
You can access your SQL database from the command line as well. You just need to log in. You will begin with:
- Opening the terminal accessibility
- Type ssh to the server
- If you are logged in, try accessing the SQL database. For providing access to the user, start typing the code psql -U username -d database name here, psql is the command for invoking the database, -U is used for providing a username, and -d is used to provide database name. After this command line code, you will see find that the prompt will be changed to the name of the database. So, you can now access the SQL database.
- For a test to check the accessibility of SQL database, type dt it is used to display all the tables containing data from your database.
Working on a dataset for tables
Try using a small set of data in the beginning for practicing before moving on to bigger ones. Once you have collected your data, you need to build the table. So, for creating the table, type in the code given below:
CREATE TABLE school (
Student varchar (20),
Roll no integer PRIMARY KEY,
Marks integer
);
For ensuring that your table works fine, try dt
Now start adding the data by adding your content in the given below format.
INSERT INTO school (student, roll no., marks) VALUES
('Akshay', 1001, 500),
('Aman', 1002, 600),
('Anita', 1003, 550);
If everything is added perfectly, you will see a message on your command line at the end.
INSERT 0 20
"SELECT" essential to being a check upon
The SELECT is the major command to be learned in SQL, and the syntax is
SELECT * FROM table_name;
If you want to make some changes in the table dataset like reading, filter, aggregate, etc. you need to write the mentioned command. If you want to select all the data set from your table school, type
SELECT * FROM school;
If you want to select a particular column, type:
SELECT student marks FROM school;
If you type in a command with Limit in the end, then you will see the response with that limit only, type
SELECT * FROM school LIMIT 2;
It will print only the given limited set of lines.
Filtering particular rows with WHERE query
You can select some specific set of rows which will be based on the values obtained from "WHERE."
The command line will be
SELECT * FROM school WHERE student = 'Abdul';
Here, SELECT * FROM school is called as "base-query command."
"WHERE," it tells which specific row to be filtered with the specified value
Student = "Abdul" This will talk about the column you might be searching.
; should never be missed
Start Practicing creating your table and try running SQL query commands.
Syntax- the important part not to be missed!
- Add emphasize of your practice on the syntax where you never missed writing semicolon. If you missed, SQL let's write further but in return don't respond.
- SQL is not at all case-sensitive. You can write the command like:
Select * from school;
This command will work smoothly. The other thing to be taken care of is the sensitivity of case towards the name of the table, name of columns and values. Values are case-sensitive, and if try not following it, you may face error.
Conclusion
Well, if you get a good start at the beginning of SQL, you can easily crack the code with SQL for analyzing the dataset in the table. With all the relevant commands for a beginner, you can practice for creating, selecting, etc. SQL is simple and easy to learn, you only require following the steps in the guide thoroughly. Better paying more close attention.
Author Bio: Charles Nelson is the author of this article and has several years of experience in SQL. He has written several blogs and guides on SQL. In this article, you will learn the beginner steps and for more information, log in to RemoteDBA.com.
