Data Analyst Interview Resources

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Sample Resume Red -> action verbs Pink -> hard skill Yellow -> soft skill Cyan -> impact statement Green -> impact matrix

SELECT Syntax 1. SELECT column1, column2, ... FROM table_name; Here, column1, column2, ... are the field/column names of the table you want to select data from. 2. SELECT * FROM table_name; Here * ( star ) means all column names/fields 3. SELECT DISTINCT Syntax SELECT DISTINCT column1, column2, ... FROM table_name; The SELECT DISTINCT statement is used to return only distinct (different) values. Inside a table, a column often contains many duplicate values; and sometimes you only want to list the different (distinct) values. 4. WHERE Syntax SELECT column1, column2, ... FROM table_name WHERE condition; The SQL WHERE Clause The WHERE clause is used to filter records. It is used to extract only those records that fulfill a specified condition. WHERE Clause Example The following SQL statement selects all the customers from the country "Mexico", in the "Customers" table: Example SELECT * FROM Customers WHERE Country='Mexico' ;

1. What is concurrency control in DBMS? This is a process of managing simultaneous operations in a database so that database integrity is not compromised. The following are the two approaches involved in concurrency control: Optimistic approach – Involves versioning Pessimistic approach – Involves locking 2. What is a checkpoint in DBMS and when does it occur? A checkpoint is a mechanism where all the previous logs are removed from the system and are permanently stored on the storage disk. So, basically, checkpoints are those points from where the transaction log record can be used to recover all the committed data up to the point of crash. 3. What are groups in Tableau? A group is a combination of dimension members that make higher level categories. For example, if you are working with a view that shows average test scores by major, you may want to group certain majors together to create major categories. 4. How are nested IF statements used in Excel? The function IF() can be nested when we have multiple conditions to meet. The FALSE value in the first IF function is replaced by another IF function to make a further test. 5. Do you wanna make your career in Data Science & Analytics but don't know how to start ? https://t.me/sqlspecialist/94 Here is a complete roadmap from scratch that will make you technically strong enough to crack any Data Scientist / Analyst and also learn Pro Career Growth Hacks to land on your Dream Job.

Data Analyst Roadmap

Q.Autoencoder methods A. Autoencoder is a type of neural network where the output layer has the same dimensionality as the input layer. In simpler words, the number of output units in the output layer is equal to the number of input units in the input layer. Various techniques exist to prevent autoencoders from learning the identity function and to improve their ability to capture important ' information and learn richer representations. 1.Sparse autoencoder (SAE) 2. Denoising autoencoder (DAE) 3. Contractive autoencoder (CAE) 4. Principal component analysis. Q. L1 and L2 regularization? A. L1 regularization gives output in binary weights from 0 to 1 for the model's features and is adopted for decreasing the number of features in a huge dimensional dataset. L2 regularization disperse the error terms in all the weights that leads to more accurate customized final models. Q. How to measure the Euclidean distance betweeen the two arrays in numpy? A. Euclidean distance is defined in mathematics as the magnitude or length of the line segment between two points. There are multiple methods for measuring the euclidean methods. Method 1. In this method, we first initialize two numpy arrays. Then, we use linalg.norm() of numpy basically to compute the euclidean distance directly. Method 2. In this method, we first initialize two numpy arrays. Then, we take the difference of the two arrays, compute the dot product of the result, and transpose of the result. Then we take the square root of the answer. This is another way to implement Euclidean distance. Method 3. In this method, we first initialize two numpy arrays. Then, we compute the difference of these arrays and take their square. We take the sum of the squared elements, and after that, we take the square root in the end. This is another way to implement Euclidean distance. Q.What are the support vectors in SVM? A. Support vectors are data points that are closer to the hyperplane and influence the position and orientation of the hyperplane. Using these support vectors, we maximize the margin of the classifier. Deleting the support vectors will change the position of the hyperplane. These are the points that help us build our SVM. Q. How do you handle categorical data? A. One-Hot Encoding is the most common, correct way to deal with non-ordinal categorical data. It consists of creating an additional feature for each group of the categorical feature and mark each observation belonging (Value=1) or not (Value=0) to that group. Q. What is coerrelation? A.Correlation is a statistical measure that expresses the extent to which two variables are linearly related (meaning they change together at a constant rate). It's a common tool for describing simple relationships without making a statement about cause and effects Q. What is covariance? A. Covariance is nothing but a measure of correlation. Covariance is a measure of how much two random variables vary together. It’s similar to variance, but where variance tells you how a single variable varies, co variance tells you how two variables vary together

Here's a snippet of code written in C:

for(int i=0;i<n;i++)
{
 for(int j=0;j<n;j++)
{
//some operation
}
}

How can I write something equivalent in SQL? Solution:Alias say, you are asked to count the frequency of each color occurring in the same the table , so you can write something like this: select distinct color ,(select count(*) from colors where c.color=color) from colors c;

1. How to change a table name in SQL? This is the command to change a table name in SQL: ALTER TABLE table_name RENAME TO new_table_name; We will start off by giving the keywords ALTER TABLE, then we will follow it up by giving the original name of the table, after that, we will give in the keywords RENAME TO and finally, we will give the new table name. 2. How to use LIKE in SQL? The LIKE operator checks if an attribute value matches a given string pattern. Here is an example of LIKE operator SELECT * FROM employees WHERE first_name like ‘Steven’; With this command, we will be able to extract all the records where the first name is like “Steven”. 3. If we drop a table, does it also drop related objects like constraints, indexes, columns, default, views and sorted procedures? Yes, SQL server drops all related objects, which exists inside a table like constraints, indexes, columns, defaults etc. But dropping a table will not drop views and sorted procedures as they exist outside the table. 4. Explain SQL Constraints. SQL Constraints are used to specify the rules of data type in a table. They can be specified while creating and altering the table. The following are the constraints in SQL: NOT NULL CHECK DEFAULT UNIQUE PRIMARY KEY FOREIGN KEY