Senior Sql Developer Interview Questions

What Is The Use Of The Sign Function

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Ans: The SIGN function returns the sign of a number. The syntax for this function is shown as follows:

SIGN

This function returns values based on the following conditions:

When numeric_expression > 0 returns positive

When numeric_expression = 0 returns zero

When numeric_expression < 0 returns negative

What Are The Differences Between Oltp And Olap

OLTP stands for Online Transaction Processing, is a class of software applications capable of supporting transaction-oriented programs. An important attribute of an OLTP system is its ability to maintain concurrency. OLTP systems often follow a decentralized architecture to avoid single points of failure. These systems are generally designed for a large audience of end-users who conduct short transactions. Queries involved in such databases are generally simple, need fast response times, and return relatively few records. A number of transactions per second acts as an effective measure for such systems.

OLAP stands for Online Analytical Processing, a class of software programs that are characterized by the relatively low frequency of online transactions. Queries are often too complex and involve a bunch of aggregations. For OLAP systems, the effectiveness measure relies highly on response time. Such systems are widely used for data mining or maintaining aggregated, historical data, usually in multi-dimensional schemas.

What Are The Benefits Of Pl/sql Packages

PL/SQL packages provide several benefits. Some of them are as follows:

Enforced Information Hiding: It offers the liberty to choose whether to keep the data private or public.
Top-down Design: We can design the interface to the code hidden in the package before we actually implement the modules.
Object Persistence: Objects declared in a package specification behave like global data for all PL/SQL objects in the application. We can modify the package in one module and then reference those changes in another
Object-oriented Design: The package gives developers a stronghold over how the modules and data structures inside the package can be used.
Guaranteeing Transaction Integrity: It provides a certain level of transaction integrity.
Performance Improvement: The RDBMS automatically tracks the validity of all program objects stored in the database. It also enhances the performance of packages.

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What Do You Mean By Database

Ans: A database is a structured form of data storage where data can be retrieved and managed efficiently. It is the collection of tables where the data is stored in an organized way. Tables consist of rows and columns in which rows are also known as records or tuples, and columns are known as attributes. Bank Management Database and University Management Database are a few examples of databases.

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What Does The Sql Server Agent Windows Service Do

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SQL Server Agent is a Windows service that handles scheduled tasks within the SQL Server environment . The jobs are stored/defined within SQL Server, and they contain one or more steps that define what happens when the job runs. These jobs may run on demand, as well as via a trigger or predefined schedule. This service is very important when determining why a certain job did not run as planned often it is as simple as the SQL Server Agent service not running.

What Do You Mean By Etl In Sql

ETL in SQL represents Extract, Transform and Load.

Extracting It is about extracting data from the source, which can be a data warehouse, CRMs, databases, etc.

Transforming It includes many processes such as cleansing, standardization, deduplication, verification, and sorting.

Loading It is the process of loading the transformed data into the new destination. There are two types of loading data: full loading and incremental loading.

What Do You Mean By Data Quality Services

Ans: DQS is nothing but a knowledge-driven data quality platform that supports carrying out data quality tasks such as correction, enrichment, standardization, and de-duplication of data. In addition, DQS analyses the integrity of data using profiling that is integrated with data-quality tasks.DQS consists of two components: Data Quality Server and a Data Quality Client.

Describe The Difference Between An Outer And Inner Join

This question focuses on the knowledge of SQL configuration.A linked server object allows you to create distributed queries where the required data sources exist in disparate systems. For example, data for your query may exist in a database on one server and data from a database on another server. You can even join to a non-SQL Server datasource, provided there is an appropriate data provider for the external database. Through SSMS, you’ll need to create a linked server through the Object Explorer or through T-SQL.

Written by Edward Danganan on May 4th, 2021

Sql Interview Questions And Answers To Know

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Here are the essential SQL interview questions and answers to know to prepare for your big day and land the SQL job of your dreams.

The technical part of your employment process is quickly approaching. To get through it, youre going to need to answer some tough SQL interview questions.

There are going to be scenarios to explain, sample SQL queries to write, and commands to define, among other things.

Well, youve come to the right place!

Whether youre looking to land a position as a database administrator, QA tester, software engineer, or business analyst, youll find the most important SQL interview questions to practice below.

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Dont worry, youre not expected to be a technical expert yourself to be able to use DevSkiller. Our own experts have created ready-to-use SQL developer interview questions and tests which are specially designed to be easy for recruiters to get the best out of. This means you can verify the technical skills of the candidates screened regardless of your own level of technological skill. You can prepare a test from scratch if required.

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What Is A Cursor Why Is It Required

A cursor is a temporary work area that is created in system memory when an SQL statement is executed. A cursor contains information on a select statement and the row of data accessed by it. This temporary work area stores the data, which is retrieved from the database, to manipulate it. A cursor can hold more than one row but can process only one row at a time. A cursor is required to process rows individually for queries.

Q32 How To Create A Temp Table In Sql Server

Temporary tables are created in TempDB and are erased automatically after the last connection is closed. We may use Temporary Tables to store and process interim results. When we need to store temporary data, temporary tables come in handy. The following is the syntax for creating a Temporary Table:CREATE TABLE #Employee ) INSERT INTO #Employee VALUES ,

Lets move to the next question in this SQL Interview Questions.

Q33. How to install SQL Server in Windows 11?

Install SQL Server Management Studio In Windows 11

Step 1: Click on SSMS, which will take you to the SQL Server Management Studio page.

Step 2: Moreover, click on the SQL Server Management Studio link and tap on Save File.

Step 3: Save this file to your local drive and go to the folder.

Step 4: The setup window will appear, and here you can choose the location where you want to save the file.Step 5: Click on Install.Step 6: Close the window after the installation is complete.Step 7: Furthermore, go back to your Start Menu and search for SQL server management studio.

Step 8: Furthermore, double-click on it, and the login page will appear once it shows up.

Step 9: You should be able to see your server name. However, if thats not visible, click on the drop-down arrow on the server and tap on Browse.

Step 10: Choose your SQL server and click on Connect.

After that, the SQL server will connect, and Windows 11 will run good.

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What Are The Different Types Of Backups Used In Sql Servers

Ans:

Copy-only backup: It is a special-use backup that is independent of the regular backups
Data backup: It is a backup of data either entirely or partially
Database backup: It is a backup of a complete database
Differential backup: It is a record of only the changes made in a database after a database backup event
Full backup: It is a backup of full data with the necessary transaction log for restoration
Log backup: It is a backup of all transaction logs
File backup: It is a backup of files in a database
Partial backup: It is a backup of files from a specific filegroup such as primary, every read/write, and optionally specified read-only files.

What Is The Difference Between Delete And Truncate Statements

The TRUNCATE command is used to delete all the rows from the table and free the space containing the table.The DELETE command deletes only the rows from the table based on the condition given in the where clause or deletes all the rows from the table if no condition is specified. But it does not free the space containing the table.

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What Is Meant By Referential Integrity

Written by Edward Danganan on May 4th, 2021

Q3 What Do You Mean By Dbms What Are Its Different Types

SQL Interview Questions And Answers | SQL Interview Preparation | SQL Training | Simplilearn

A Database Management System is a software application that interacts with the user, applications, and the database itself to capture and analyze data. A database is a structured collection of data.

A DBMS allows a user to interact with the database. The data stored in the database can be modified, retrieved and deleted and can be of any type like strings, numbers, images, etc.

There are two types of DBMS:

Relational Database Management System: The data is stored in relations . Example MySQL.
Non-Relational Database Management System: There is no concept of relations, tuples and attributes. Example MongoDB

Lets move to the next question in this SQL Interview Questions.

What Do You Mean By Subquery

It is a query that exists inside the statements such as SELECT, INSERT, UPDATE, and DELETE. It may exist inside a subquery too. A subquery is also known as an inner query or inner select. The statement with a subquery is an outer query or outer select.

Lets see the example shown below in which the maximum unit price is the result that will be returned by the subquery using the SELECT statement. Also, orders is the value that will be returned by the outer query using the SELECT statement.

What Do You Understand About A Temporary Table Write A Query To Create A Temporary Table

A temporary table helps us store and process intermediate results. Temporary tables are created and can be automatically deleted when they are no longer used. They are very useful in places where temporary data needs to be stored.

Syntax:

CREATE TABLE #table_name The below query will create a temporary table:create table #bookNow, we will insert the records.insert into #book valuesinsert into #book valuesselect * from #book

Output:

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Q26 What Are Union Minus And Intersect Commands

The UNION operator is used to combine the results of two tables while also removing duplicate entries.

The MINUS operator is used to return rows from the first query but not from the second query.

The INTERSECT operator is used to combine the results of both queries into a single row.Before running either of the above SQL statements, certain requirements must be satisfied

Within the clause, each SELECT query must have the same amount of columns.

The data types in the columns must also be comparable.

In each SELECT statement, the columns must be in the same order.

Lets move to the next question in this SQL Interview Questions.

Brief The Different Types Of Joins

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Ans:

INNER JOIN: This command helps to return records that are common to both the tables
LEFT JOIN: This command helps to return values that are common to each other along with the complete records of the left table
RIGHT JOIN: This command helps to return values that are common to each other along with the complete records of the right table
FULL JOIN: This command helps return all the tables’ records when there is a match between the two.
CROSS JOIN: It is known as Cartesian Join. This command returns all combinations of each row from the tables. There is no specific condition for joining two tables.

Q8 What Are Union Minus And Intersect Commands

The UNION operator is used to combine the results of two tables while also removing duplicate entries. The MINUS operator is used to return rows from the first query but not from the second query. The INTERSECT operator is used to combine the results of both queries into a single row. Before running either of the above SQL statements, certain requirements must be satisfied Within the clause, each SELECT query must have the same amount of columns. The data types in the columns must also be comparable. In each SELECT statement, the columns must be in the same order.

What Are Tables And Fields

A table is a set of data that are organized in a model with Columns and Rows. Columns can be categorized as vertical, and Rows are horizontal. A table has specified number of column called fields but can have any number of rows which is called record.

Example:.

Field: Emp ID, Emp Name, Date of Birth.

Data: 201456, David, 11/15/1960.

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How To Install Sql

SQL stands for Structured Query Language and it is not something you can install. To implement sql queries, you would need a relational database management system. There are different varieties of relational database management systems such as:

Hence, to implement sql queries, we would need to install any of these Relational Database Management Systems.

What Do You Mean By Rdbms

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Ans: RDBMS is nothing but Relational DataBase Management System. It is the software that allows storing, managing, querying, and retrieving data from a relational database. And RDBMS interacts with users and the database it can also carry out administrative tasks such as managing data storage, accessing data, and assessing database performance.

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Describe How To Delete Duplicate Rows Using A Single Statement But Without Any Table Creation

Let us create an employee table where the column names are ID, NAME, DEPARTMENT, and EMAIL. Below are the SQL scripts for generating the sample data:

CREATE TABLE EMPLOYEE,DEPARTMENT INT,EMAIL Varchar)INSERT INTO EMPLOYEE VALUES INSERT INTO EMPLOYEE VALUES INSERT INTO EMPLOYEE VALUES INSERT INTO EMPLOYEE VALUES These are the duplicate rows:INSERT INTO EMPLOYEE VALUES INSERT INTO EMPLOYEE VALUES

We can see the duplicate rows in the above table.

DELETE e1 FROM EMPLOYEE e1, EMPLOYEE e2 WHERE e1.name = e2.name AND e1.id >  e2.id

The SQL query above will delete the rows, where the name fields are duplicated, and it will retain only those unique rows in which the names are unique and the ID fields are the lowest, i.e., the rows with IDs 5 and 6 are deleted, while the rows with IDs 1 and 2 are retained.