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Showing posts with the label SQL Queries

### 5 SQL Queries That Popularly Used in Data Analysis

Here are five popular SQL queries frequently used in data analysis. 1. SELECT with Aggregations Summarize data by calculating aggregates like counts, sums, averages, etc. SELECT department, COUNT(*) as employee_count, AVG(salary) as average_salary FROM employees GROUP BY department; 2. JOIN Operations  Combine data from multiple tables based on a related column. SELECT e.employee_id, e.name, d.department_name FROM employees e JOIN departments d ON e.department_id = d.department_id; 3. WHERE Clause for Filtering Filter records based on specified conditions. SELECT * FROM sales WHERE sale_date BETWEEN '2024-01-01' AND '2024-12-31'   AND amount > 1000; 4. ORDER BY Clause for Sorting Sort results in ascending or descending order based on one or more columns. SELECT product_name, price FROM products ORDER BY price DESC; 5. GROUP BY with HAVING Clause Group records and apply conditions to the aggregated results. SELECT department, SUM(salary) as total_salaries FROM employ

# 5 Commonly Asked SQL Queries in Interviews

Here are the five top commonly asked SQL queries in the interviews. These you can expect in Data Analyst, or, Data Engineer interviews. SQL Queries for Interviews 01. Joins The commonly asked question pertains to providing two tables, determining the number of rows that will return on various join types, and the resultant. Table1 -------- id ---- 1 1 2 3 Table2 -------- id ---- 1 3 1 NULL Output ------- Inner join --------------- 5 rows will return The result will be: =============== 1  1 1   1 1   1 1    1 3    3 02. Substring and Concat Here, we need to write an SQL query to make the upper case of the first letter and the small case of the remaining letter. Table1 ------ ename ===== raJu venKat kRIshna Solution: ========== SELECT CONCAT(UPPER(SUBSTRING(name, 1, 1)), LOWER(SUBSTRING(name, 2))) AS capitalized_name FROM Table1; 03. Case statement SQL Query ========= SELECT Code1, Code2,      CASE         WHEN Code1 = 'A' AND Code2 = 'AA' THEN "A" | "AA&qu

# How to Call SQL Query from Python

Python's top supported database is MySQL. You can run SQL queries from Python. Here're best examples of how to connect to MYSQL and access MYSQL tables from Python. Read:  How to Print String in Next Line Easily Here are Steps Import MySQL connecter Give user id, password details Issue SQL query Python Logic to import MySQL connector import mysql.connector Note: If the MySQL connecter not installed in python, you need to install it using the below command. pip3 install mysql-connector-python --allow-external mysql-connector-python Supply user id and Password conn=mysql.connector.connect(user='root', password='password', host='localhost', database='sakila') mycursor=conn.cursor() Issue SQL Query mycursor.execute("show tables") # you won't see any result. You need to give print. print(mycursor.fetchall()) mycursor.execute("select * from customer") # you won't see any result. You need to give print. print(mycursor.fetchal