No matter either you work in an IT company, education sector or medical center, you need to handle a lot of data. Programming languages like R and Python are quite promising for data science. However, SQL is the first thing that comes to our mind whenever we hear the word data.
SQL mainly stands for Structured Query Language. It is a standard database language that is used to create, maintain and retrieve relational databases. It was first used in the 1970s. SQL is a very important tool for data scientists.
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SQL Features for Data Scientists
SQL comes with some easy to understand features. These features help in organizing and retrieving data. In this article, we will discuss the top 5 handy features of SQL. So, here we go:
1. Selection of statement
A data scientist needs to select a lot of data from different tables for getting statistics, patterns and much more. For this purpose, one can use the basic query
select * from <table name>;
But this will return several records. What if you need only need a few columns in a table?
select <column1>, <column2> from <table name>;
The above query will help you to select the column you want.
2. Grouping and Sorting
This feature is quite helpful especially when you are working with a subset of data. For example, if you want the number of students aged between 10 to 15, you simply can use the query-
select name, age from student where age between 10 and 15;
Similarly, you can count the number of students from each branch/department. You can use the following query
select count(student_id), deptt from student group by deptt;
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3. String functions
SQL comes with several string functions that are very helpful. These features allow you to do work faster.
Upper and Lower Case
This is especially helpful when you want to print something in a respective case either upper or lower. The following query will help to print student’s first name in lowercase.
select LOWER(first_name) from student;
This feature will join different columns or strings. If you want to display the first name plus last name as a full name, concat can help you through this.
select CONCAT(first_name, ‘ ‘, last_name) as fullName from student;
4. Data Handling
Handling data is quite complex but with SQL this can be done quite easily. There are features that help one to analyze data. These functions are as follows:
- DATEADD– It adds one year to an existing date.
- TO_ DATE- It converts a string into a date.
- DATEPART– It helps you to get a particular part of the date ( year, month or day)
- DATEDIFF– It helps to find the differences between the 2 given dates.
This feature is quite useful for finding the sum (SUM), average (AVG), minimum (MIN), maximum (MAX) and count (COUNT) values from a data set.
select AVG(total_marks) from students group by deptt;
The above query can help you to know the average percentage of marks obtained by the students of each department collectively.
Though there are many features of SQL, we have discussed only a few features. We have listed only 5 handy features of SQL that are useful for data scientists. Hope you have liked the article and found it useful.