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SQL Interview Success: Unlocking the Top 5 Frequently Asked Queries

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 Here are the five top commonly asked SQL queries in the interviews. These you can expect in Data Analyst, or, Data Engineer interviews. Top 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" | "A
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15 Top Data Analyst Interview Questions: Read Now

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We will explore the world of data analysis using Python, covering topics such as data manipulation, visualization, machine learning, and more. Whether you are a beginner or an experienced data professional, join us on this journey as we dive into the exciting realm of Python analytics and unlock the power of data-driven insights. Let's harness Python's versatility and explore the endless possibilities it offers for extracting valuable information from datasets. Get ready to level up your data analysis skills and stay tuned for informative and practical content!


Data Analyst Interview Questions


Python Data Analyst Interview Questions


01: How do you import the pandas library in Python? 


A: To import the pandas library in Python, you can use the following statement: import pandas as pd.


Q2: What is the difference between a Series and a DataFrame in pandas? 


A: A Series in pandas is a one-dimensional labeled array, while a DataFrame is a two-dimensional labeled data structure with columns of potentially different types.


Q3: How do you read a CSV file into a DataFrame using pandas? 


A: To read a CSV file into a DataFrame using pandas, you can use the read_csv() function. For example: df = pd.read_csv('filename.csv').


Q4: What is the purpose of the NumPy library in Python analytics? 


A: The NumPy library in Python analytics is used for numerical computing. It provides mathematical functions and tools for working with multidimensional arrays, which are used by other libraries like pandas and scikit-learn.


Q5: How do you perform data cleaning and preprocessing using pandas? 


A: Data cleaning and preprocessing using pandas can involve tasks such as handling missing values, removing duplicates, transforming data types, and normalizing data.


Q6: How do you calculate descriptive statistics (mean, median, etc.) using pandas? 


A: To calculate descriptive statistics using pandas, you can use functions like mean(), median(), std(), min(), max(), and describe().


Q7: How do you handle missing values in a DataFrame? 


A: In pandas, missing values can be handled using functions like isnull(), fillna(), and dropna().


Q8: How do you merge/join multiple DataFrames in pandas? 


A: To merge/join multiple DataFrames in pandas, you can use functions like concat(), merge(), and join().


Q9: How do you perform groupby operations and aggregations in pandas? 


A: Groupby operations and aggregations in pandas can be performed using the groupby() function.


Q10: How do you visualize data using matplotlib or seaborn libraries in Python? 


A: Data visualization in Python can be done using libraries like matplotlib and seaborn.


Q11: What is the purpose of the scikit-learn library in Python analytics? 


A: The scikit-learn library in Python analytics is used for machine learning tasks.


Q12: How do you split data into training and testing sets using scikit-learn? 


A: To split data into training and testing sets using scikit-learn, you can use the train_test_split() function.


Q13: How do you perform feature scaling in scikit-learn? 


A: Feature scaling in scikit-learn is important to ensure that all features have a similar scale.


Q14: What are some commonly used machine learning algorithms in scikit-learn? 


A: Scikit-learn provides a wide range of machine learning algorithms, including linear regression, logistic regression, decision trees, random forests, support vector machines, k-nearest neighbors, and neural networks.


Q15: How do you evaluate the performance of a machine learning model using metrics like accuracy, precision, and recall? 


A: The performance of a machine learning model can be evaluated using metrics like accuracy, precision, recall, and F1 score.

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