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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

SQL Vs NOSQL real differences to read today

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SQL and NoSQL both or two different languages that will be used on different databases. In resolving bigdata analytics NoSQL is most popular. Where as SQL is popular in relational databases. SQL Vs NOSQL Top Differences SQL SQL is structured query language  It was first commercial language used in RDBMS  SQL language is divided into multiple sub elements NoSQL Data is not in one machine or even one network.  Data can be any type public data and private data  Huge volume of data so you cannot put it in one place.  It is uncoordinated in time as well as space.  It is not always nice, structured data that SQL was meant to handle. Also Read RDBMS Vs NoSQL Databases top differences

5 Top features of Columnar Databases (1 of 2 )

The traditional RDBMS - Since the days of punch cards and magnetic tapes, files have been physically contiguous bytes that are accessed from start (open file) to finish (end-of-file flag = TRUE). Yes, the storage could be split up on a disk and the assorted data pages connected by pointer chains, but it is still the same model. Then the file is broken into records (more physically contiguous bytes), and records are broken into fields (still more physically contiguous bytes). A file is processed in record by record (read/fetch next) or sequentially navigated in terms of a physical storage location (go to end of file, go back/forward n records, follow a pointer chain, etc.). There is no parallelism in this model. There is also an assumption of a physical ordering of the records within the file and an ordering of fields within the records. A lot of time and resources have been spent sorting records to make this access practical; you did not do random access on a magnetic tape and you co

4 Modern databases Every Developer Should Know

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Below is the complete list of NoSQL databases currently available in the market. NoSQL Databases 1. Sorted Order Column Oriented Stores Google's Bigtable espouses a model where data is stored in a column-oriented way. This contrasts with the row-oriented format in RDBMS. The column-oriented storage allows data to be stored effectively. It avoids consuming space when storing nulls by simply not storing a column when a value doesn't exist for that column. Each unit of data can be thought of as a set of key/value pairs, where the unit itself is identified with the help of a primary identifier, often referred to as the primary key. Bigtable and its clones tend to call this primary key to the row-key. Example: The name column-family bucket stores the following values:  For row-key: 1  first_name: John  last_name: Doe  For row-key: 2  first_name: Jane T he location column-family stores the following: For row-key: 1 zip_code: 10001 For row-key: 2 zip_code:

Big Data: Top NoSQL Interview Questions (2 of 5)

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1) What is most important character of NoSQL? High Availability 2)Different types of NoSQL databases? Key-Value stores Column Stores Graph Stores Document Stores 3)What is oracle NoSQL database? Oracle NoSQL Database is a distributed key-value database designed to provide highly reliable, scalable, and available data storage across a configurable set of systems. 4)What is the DB engine being used in Oracle NoSQL database? Oracle NoSQL Database uses Oracle Berkeley DB Java Edition as the underlying data storage engine. 5)What is oracle NoSQL database? Oracle NoSQL Database is a shared-nothing system designed to run and scale on commodity hardware. Key-value pairs are hash partitioned across server groups known as shards. At any point in time, a single key-value pair is always associated with a unique shard in the system. 6) What are unique features of Oracle NoSQL? Oracle NoSQL Database leverages the high availability features in Berkeley DB in order to provide res

10 Top NoSQL Database Recently Asked Interview Questions

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1) Who is involved in developing NoSQL? Amazon and Google Papers 2) What is NoSQL? You can use NoSQL on non-relational databases. Like columnar databases, by using NoSQL, you can query data from non-relational databases. 3) What are the unique features of NoSQL databases? no relationship between records need Un-structural data store data that individual records do not have a relationship with each other 4) How NoSQL-databases are faster than traditional RDBMS? Stores database on multiple servers, rather than storing the whole database in a single server Adding replicas on other servers, we can retrieve data faster even one of the servers crashes 5) What are the UNIQUE features of NoSQL? Opensource ACID complaint 6) What are the characteristics of a good NoSQL product? High availability: Fault tolerance when a single server goes down Disaster recovery: For when a data center goes down, or more likely, someone digs up a network cable just outside the data center Support: Someone to st

RDBMS Vs NOSQL awesome differences to read now

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NoSQL and RDBMS or SQL are different from each other. You may ask what is the difference. Below explained in a way that you can understand quickly. 💡Traditional Database A schema is required. All traditional data warehouses using RDBMS to store datamarts. Databases understand SQL language. It has a specific format and rules to interact with traditional databases. Less scalable. It has certain limitations.  Expensive to make the databases as scalable Data should be in a certain format. Data stored in row format. NoSQL database The growing internet usage and involving a number of devices caused to invent databases that have the capability to store any kind of data. More: MongoDB 3.2 fundamentals for Developers-Learn with Exercises NoSQL Special Features The schema is not required. Ability to handle multiple data types. This is the power of NoSQL. NoSQL is much suitable for analytical databases. Since those should be flexible, scalable, and able to store any f

MemSQL in Advanced Data Analytics

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Why use a battery of "complicated" and "immature" tools like Kafka, Zookeeper, and NoSQL databases to support low-latency big data applications when you can use a durable, consistent, SQL-compliant in-memory database? This is the question NewSQL in-memory database vendors MemSQL and VoltDB are posing to big-data developers who are trying to build real-time applications. MemSQL this week announced a two-way, high-performance MemSQL Spark Connector designed to complement the fast-growing Apache Spark in-memory analytics platform.   "There's a lot of excitement about Spark, but many data scientists struggle with complexity and the high degree of expertise to work with related data pipelines," said Erik Frenkiel, CEO and cofounder of MemSQL, in a phone interview with InformationWeek. "As a database, MemSQL offers durability and transaction support, so it can simplify those real-time data pipelines, providing the ability to ingest data and qu

Data Analytics Key Role of NOSQL

Traditional database theory dictates that you design the data set before entering any data. A data lake, also called an enterprise data lake or enterprise data hub, turns that model on its head, says Chris Curran, principal and chief technologist in PricewaterhouseCoopers’ U.S. advisory practice.  “It says we’ll take these data sources and dump them all into a big Hadoop repository, and we won’t try to design a data model beforehand,” he says. Instead, it provides tools for people to analyze the data, along with a high-level definition of what data exists in the lake. “People build the views into the data as they go along. It’s a very incremental, organic model for building a large-scale database,” Curran says. On the downside, the people who use it must be highly skilled Speed of NOSQL Alternatives to traditional SQL-based relational databases, called NoSQL (short for “Not Only SQL”) databases, are rapidly gaining popularity as tools for use in specific kinds of analytic applica