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SQL Statements for 80% of Your Data Science Tasks

Structured Query Language (SQL) is a programming language used to manage and manipulate relational databases. SQL is used by data analysts and data scientists for extracting, transforming, and analyzing data stored in databases. In this blog, we will discuss the most commonly used SQL functions that are used in real-world problems and can help solve up to 80% of the work required in data analysis.

SELECT:

SELECT is the most frequently used SQL function. It is used to retrieve data from one or more tables in a database. This function allows you to select specific columns, rows, or a combination of both from a table. The syntax for the SELECT statement is:

SELECT column_name(s) FROM table_name


WHERE:

The WHERE function is used to filter data from a table based on a specific condition. It is used in combination with the SELECT function to retrieve specific data. The syntax for the WHERE statement is:

SELECT column_name(s) FROM table_name WHERE condition


GROUP BY:

The GROUP BY function is used to group data based on one or more columns in a table. It is used in combination with the SELECT function to aggregate data and calculate summary statistics such as the sum, average, or count of data for each group. The syntax for the GROUP BY statement is:

SELECT column_name(s), aggregate_function(column_name) 

FROM table_name 

WHERE condition 

GROUP BY column_name(s)


JOIN:

The JOIN function is used to combine data from two or more tables based on a common column. It is used to retrieve data from multiple tables that have a relationship. There are different types of joins such as INNER JOIN, LEFT JOIN, RIGHT JOIN, and FULL JOIN. The syntax for the JOIN statement is:

SELECT column_name(s) 

FROM table1 

JOIN table2 

ON table1.column_name = table2.column_name


ORDER BY:

The ORDER BY function is used to sort the data retrieved from a table in ascending or descending order. It is used to arrange data in a specific order for better analysis. The syntax for the ORDER BY statement is:

SELECT column_name(s) 

FROM table_name 

ORDER BY column_name(s) ASC/DESC


COUNT:

The COUNT function is used to count the number of rows in a table that meets a specific condition. It is combined with the WHERE function to count the number of rows that satisfy a specific condition. The syntax for the COUNT statement is:

SELECT COUNT(column_name) 

FROM table_name 

WHERE condition


SUM:

The SUM function is used to calculate the sum of a column in a table. It is combined with the WHERE function to calculate the sum of a specific column that satisfies a specific condition. The syntax for the SUM statement is:

SELECT SUM(column_name) 

FROM table_name 

WHERE condition


AVG:

The AVG function is used to calculate the average value of a column in a table. It is combined with the WHERE function to calculate the average value of a specific column that satisfies a specific condition. The syntax for the AVG statement is:

SELECT AVG(column_name) 

FROM table_name 

WHERE condition


MAX:

The MAX function is used to retrieve the maximum value of a column in a table. It is combined with the WHERE function to retrieve the maximum value of a specific column that satisfies a specific condition. The syntax for the MAX statement is:

SELECT MAX(column_name) 

FROM table_name 

WHERE condition


MIN:

The MIN function is used to retrieve the minimum value of a column in a table. It is combined with the WHERE function to retrieve the minimum value of a specific column that satisfies a specific condition. The syntax for the MIN statement is:

SELECT MIN(column_name) 

FROM table_name 

WHERE condition


In conclusion, the above functions are the most commonly used functions in SQL that can help solve real-world problems. 

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