Some of the common SQL interview questions for business analysts are “What Is SQL?”, “What Do You Use To Get Non-Repeated Values?”, “What Are The Aggregate Functions?”, “What Is Self Join?”, “What Is The Difference Between Left Join And Right Join?”, “What Is A Subquery?”, etc.
Key Takeaways
- SQL stands for the structured query language and it enables you to perform various tasks quickly and efficiently
- Good command of SQL has become mandatory for business analyst professionals
- One key role of a business analyst is to expand existing business methods
- The knowledge of SQL will provide you a better understanding of data flow in information systems
What Is A Business Analyst?
A business analyst analyzes a variety of business processes for a company. So a business analyst must have proper knowledge of finance, economics, and IT systems. A business analyst has to work on the integration of data flows between systems, supervision of business applications monitoring, and analysis of financial data. Business analysts develop and maintain analytical tools as well as deal with the quality of data in information systems. In fact, a business analyst works as a communication bridge between the IT and business teams. Some other working areas of a business analyst are:
1. Recognize what business does and how it does
2. Determine how to expand existing business methods
3. Classify the steps or tasks to support the execution of new features
4. Design the new features to implement
5. Evaluate the impact of executing new features
6. Implement the new features
Different Business Analyst Role
The role of a business analyst may vary depending on the sector. So business analysts are classified into various categories like:
1. Business Analyst
2. Business Process Analyst
3. IT Business Analyst
4. Business System Analyst
5. System Analyst
6. Data Analyst
7. Functional Architect
8. Usability or UX Analyst
Required Skills Of A Business Analyst
According to the IIBA some of the most important skills of a business analyst are:
1. Oral and written communication skills
2. Interpersonal and consultative skills
3. Facilitation skills
4. Analytical thinking and problem solving
5. Being detail-oriented and capable of delivering a high level of accuracy
6. Organizational skills
7. Knowledge of the business structure
8. Stakeholder analysis
9. Requirements engineering
10. Costs benefit analysis
11. Processes modeling
12. Understanding of networks, databases, and other technology
Why SQL Is Important For Business Analysts
The knowledge of SQL will help you better understand the documents that are made from the results from databases. Moreover, you will be able to do deep research on the results as well as the data stored in relational databases. Therefore, SQL for business analyst positions is becoming more demanding and it’s not a nice-to-have skill anymore. The knowledge of SQL will provide you a better understanding of data flow in information systems so you can easily create reports and apply them as business strategies.
SQL Interview Questions For Business Analysts With Answers
What Is SQL?
A structured query language is known as SQL. SQL is mainly used for communicating with relational databases. This is a widely used language in most database management systems like Oracle, MySQL, PostgreSQL, etc. When you work with relational databases, SQL will help you retrieve, update, insert, and delete data.
What Do You Use To Get Non-Repeated Values?
If you want to get the non-repeated values then you have to use the DISTINCT operator in the SELECT clause. Here is the format –
SELECT DISTINCT
column1, column2, …
FROM
table1;
If you use the DISTINCT for one column then the database system uses that column to evaluate duplicate. If you use the DISTINCT for two or more columns then the database system will use the combination of values in these columns for the duplication check.
What Is The IN Operator?
The IN condition also known as IN operator lets you easily test if an expression matches any value in a list of values. Usually, IN operator is used in the WHERE clause and is shorthand for multiple OR conditional statements. If the expression that proceeds IN matches any of the elements in the list, the resulting value is TRUE, or 1; otherwise, the value is FALSE, or 0.
What Are The Aggregate Functions?
Aggregate functions are used to perform the calculation on a set of values and return a single value. The common aggregate functions are:
1. AVG – calculates the average of a set of values
2. COUNT – counts rows in a specified table or view
3. MIN – gets the minimum value in a set of values
4. MAX – gets the maximum value in a set of values
5. SUM – calculates the sum of values
What Is The Group By Statement Used For?
The GROUP BY is a very commonly used SQL command and it is used to group rows that have the same values. You have to use this command for the SELECT statement. You can also use this command with aggregate functions to produce summary reports from the database. Moreover, the GROUP BY command follows the WHERE clause in a SELECT statement and precedes the ORDER BY clause.
In What Situations Should You Use Where And Having In A Statement?
Both WHERE and HAVING are used to filter records but there is a significant difference between these two commands. The WHERE command is used to filter records from a result, whereas the HAVING command is used to filter groups. In case you are using both commands, you have to use the WHERE command first and then you have to use the HAVING command.
What Is Self Join?
Self-JOIN is mostly used to join a table with itself as if the table were two tables. If you want to compare the values of a particular column with other values in the same column of the same table then you have to use the self JOIN command. This command temporarily renames at least one table in the SQL statement.
What Is Cross Join?
This command is used to produce result sets of two or more joined tables. Here, the number of rows in the first table is multiplied by the number of rows in the second table.
What Is Inner Join?
This is a very common type of join and it is used to identify the overlap, or intersection, between two sets of data. When you use the INNER JOIN, it returns all the rows that are shared by two tables. This command compares each row of table1 with each row of table2 to find all pairs of rows which satisfy the join-predicate.
What Is The Difference Between Left Join And Right Join?
The LEFT JOIN will return the records from the left table and if the record doesn’t match the right table then it will become NULL. The same goes for the RIGHT JOIN as it returns the records from the right table and if the record doesn’t match the left table then it will become NULL.
What Is The Difference Between Union And Union All?
Both UNIQUE and UNIQUE ALL work similarly, except that UNION ALL selects all the values. The UNION command will omit duplicate records but the UNION ALL will include duplicate records.
What Is A Subquery?
A subquery is a query within another query. Usually, this type of query is nested inside a SELECT, INSERT, UPDATE, or DELETE statement. You can use a subquery anywhere; where can be used anywhere an expression is allowed. Here, the outer query is the main query and the inner query is the subquery. You have to execute the subquery first and its result will be passed on to the main query.
What Are The Different Types Of Subqueries?
There are three types of subqueries. They are:
1. Single Row Sub Query: This type of subquery returns single row output
2. Multiple row subquery: This type of subquery returns multiple row output
3. Correlated Sub Query: A correlated subquery uses values from the outer query so it depends on the outer query
What Is The Primary Key?
A PRIMARY KEY is used as a unique identifier for a particular record in a table. A PRIMARY KEY can’t be NULL and it must contain UNIQUE values. You can only use one PRIMARY KEY for a particular table. This primary key can consist of single or multiple columns.
What Is A View?
In SQL, a VIEW is a virtual table that consists of a subset of data from a table. The field of view is consisting of one or more real tables in the database. Moreover, you can also add SQL functions, WHERE, and JOIN statements to a view and make it look like the data is coming from a single table.
What Is A Database Transaction?
A database transaction is a sequence of operations that must be executed. It is a single logical unit of work that has a defined beginning and end. The benefit of using transactions is data integrity.
What Is Database Normalization?
Database Normalization is the process to reduce redundancy and improve the data integrity of a database. Some other key advantages of Database Normalization are:
1. To eliminate redundant or useless data
2. To reduce the complexity of the data
3. To ensure the relationship between tables as well as data in the tables
4. To ensure data dependencies and data is logically stored
How To Find Out The Constraint Information In SQL?
There are two quires that you can use to find out the Constraint Information in SQL. They are:
SELECT * From User_Constraints;
SELECT * FROM User_Cons_Columns;
What Query You Can Use To Find Out Maximum And Minimum Marks In SQL?
Below is the query you can use to find out maximum and minimum marks in SQL –
Select max (marks) from Student
Union
Select min (marks) from Student;
What Are The Different Set Operators In SQL?
Set operators connect two tables and fetch the records from the two tables. You have to make sure the data types are the same for both tables. Here are the 4 different Set operators in SQL:
1. Union
2. Union all
3. Intersect
4. Minus
What Are The Basic Types Of Joins?
There are two basic types of joins:
1. Joins using Operators: Equi Join, Non-Equi Join
2. Joins using Concepts: Inner Join, Outer Join, Cross Join, Self Join
What Is The Difference Between Joins And Union?
You can use both JOINS and UNION to combine data from one or more tables into a single result but both the commands do it differently. The JOINS will combine data into a single table based on the given conditions between the tables. On the other hand, you can use the UNION command to combine two similar data sets to create a single table that contains all the information from tables 1 and 2.
What Is DDL?
DDL stands for Data Definition Language. In SQL; DDL is used for creating and modifying database objects such as tables, indexes, etc. You can use the DDL to add, remove, or modify tables within a database. Different DDL statements are:
1. CREATE: Creates a new table, a view of a table, or another object in the database
2. ALTER: Modifies an existing database object, such as a table
3. DROP: Deletes an entire table, a view of a table, or another object in the database
What Are The Different Types Of Indexes?
There are eight types of indexes available in SQL. They are:
1. Normal index
2. Unique Index
3. Bit Map Index
4. Composite Index
5. B-Tree Index
6. Function-Based Index
7. Clustered Index
8. Non-Clustered Index
What Is The Difference Between NVL, NVL2, And Nullify?
IN SQL, the NVL converts the null value to an actual value. On the other hand, NVL 2 works differently. If the first expression is not null, then the NVL2 function returns the second expression. If the first expression is null, then it will return the third expression. The NULLIF compares expression 1 and expression 2. If the expressions are equal then it will return NULL. If the expressions are not equal then it will return the expression 1.
What Is Mean By SQL Scalar Functions?
For SQL Scalar Functions you will get single output for each row. Moreover, the input range of this type of function is one-dimensional. While using this function you will get the value of every row which we are used in the query to process. Some important SQL Scalar Functions are:
1. UCASE() – Converts a field to upper case
2. LCASE() – Converts a field to lower case
3. SUBSTR() – Extract characters from a text field
4. LEN()/LENGTH() – Returns the length of a text field
5. ROUND() – Rounds a numeric field to the number of decimals specified
What Is Rank Function In SQL?
The Rank function is a window function and you can use it to return the rank of rows in the table within a group of rows. Depending on the function you might receive the same value for some rows. So if you want to find out the rank of a specific row in the table then you have to use this function.
What Is The Difference Between Unique And Distinct?
Both the unique and distinct are the same apart from one difference. You have to use Unique before insertion and retrieval. Unique consists of non-duplicate values. On the other hand, Distinct is only used in retrieval.
What Are The Triggers In SQL?
A trigger is a stored procedure and it will automatically run when an event occurs in the database server. There are two main types of triggers: DML Triggers and DDL triggers.
DML Triggers will run when someone tries to modify data through a data manipulation language (DML) event. DML events are INSERT, UPDATE, or DELETE actions.
DDL Triggers will run on DDL statements like CREATE, ALTER, and DROP.
What Are The Different Types Of Triggers?
There are four types of Triggers in SQL. They are:
1. DDL Triggers
2. DML Triggers
3. CLR Triggers
4. Logon Triggers
What Is The Syntax For Logon Trigger?
The syntax for Logon Trigger is:
CREATE TRIGGER trigger_name
ON ALL SERVER
[WITH ENCRYPTION]
{FOR|AFTER} LOGON
AS
sql_statement [1…n ]
What Is The Syntax For Trigger?
The Syntax for Trigger is:
CREATE TRIGGER trigger_name
ON {table|view}
[WITH ENCRYPTION|EXECUTE AS]
{FOR|AFTER|INSTEAD OF} {[CREATE|ALTER|DROP|INSERT|UPDATE|DELETE ]}
[NOT FOR REPLICATION]
AS
sql_statement [1…n ]
Where Triggers Are Used In SQL?
In SQL, Triggers are mainly used in:
1. Insert Data into a table
2. Delete data from a table
3. Update table record
What Is DML?
DML stands for Data Manipulation Language. DML is used for adding, deleting, and modifying data in a database. You can use the DML to retrieve and manipulate data in a relational database.
What Are The Commands Of DML?
In DML there are lots of commands. Some commonly used commands are:
1. SELECT – retrieve data from the a database
2. SELECT <attribute>, ….., <attribute n> FROM <table name>;
3. INSERT – insert data into a table
4. INSERT INTO <table name> VALUES (<value 1>, … <value n>);
5. UPDATE – updates existing data within a table
6. UPDATE <table name> SET <attribute> = <expression> WHERE <condition>;
7. DELETE – deletes all records from a table, the space for the records remain
8. DELETE FROM <table name> WHERE <condition>;
9. MERGE – UPSERT operation (insert or update)
10. CALL – call a PL/SQL or Java subprogram
11. LOCK TABLE – control concurrency
References:
1. https://www.indeed.com/career-advice/interviewing/sql-for-business-analyst
2. https://www.complexsql.com/sql-interview-questions-for-business-analyst/
Last Updated on October 6, 2022 by Magalie D.
Magalie D. is a Diploma holder in Public Administration & Management from McGill University of Canada. She shares management tips here in MGTBlog when she has nothing to do and gets some free time after working in a multinational company at Toronto.
