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Basic SQL Knowledge Test For Beginner

photo: pexel Are you new to SQL and preparing for your first job that requires SQL knowledge?  This blog post is designed specifically for beginners like you who are just starting out on their journey with SQL. Whether you're a student, a recent graduate, or someone looking to transition into a tech role, this guide will help you build a strong foundation in SQL concepts, understand common SQL queries, and prepare you for the types of SQL tasks you might encounter in your first job. We'll break down complex concepts into easy-to-understand steps, provide practical examples, and give you tips to succeed in interviews and on the job. Let's get you job-ready with SQL! Below is the table structure for the `customer`, `user_account`, and `contact` tables in a more visual format: Below are the SQL statements to create the `customer`, `user_account`, and `contact` tables according to the schema provided: 1. `customer` Table ```sql CREATE TABLE customer (     id INT PRIMARY KEY, ...

Stream Processing Window Functions

  Photo by João Jesus: pexel A common goal of stream processing is to aggregate events into temporal intervals, or windows. For example, to count the number of social media posts per minute or to calculate the average rainfall per hour. Azure Stream Analytics includes native support for five kinds of temporal windowing functions. These functions enable you to define temporal intervals into which data is aggregated in a query. The supported windowing functions are Tumbling, Hopping, Sliding, Session, and Snapshot. No, these windowing functions are not exclusive to Azure Stream Analytics. They are commonly used concepts in stream processing and are available in various stream processing frameworks and platforms beyond Azure, such as Apache Flink, Apache Kafka Streams, and Apache Spark Streaming. The syntax and implementation might vary slightly between different platforms, but the underlying concepts remain the same. Five different types of Window functions Tumbling Window (Azure St...

Data Lake Comparison

AWS S3 (Simple Storage Service): Amazon Simple Storage Service (Amazon S3) is a scalable object storage service offered by Amazon Web Services (AWS). It provides developers and IT teams with secure, durable, and highly available storage infrastructure for a wide range of use cases, including data backup and recovery, data archiving, web and mobile applications, big data analytics, and content distribution. Key Features: 1. Scalability: Amazon S3 is designed to scale seamlessly from a few gigabytes to petabytes or more of data without any upfront provisioning. It can handle virtually unlimited amounts of data and requests. 2. Durability and Availability: S3 stores data redundantly across multiple devices and facilities within a region to ensure high durability and availability. It offers 99.999999999% (11 nines) durability and 99.99% availability SLA. 3. Security: S3 provides several security features to protect data at rest and in transit, including server-side encryption, encryption i...

Handling Large Binary Data with Azure Synapse

  Photo by Gül Işık Handling large binary data in Azure Synapse When dealing with large binary data types like geography or image data in Azure Synapse, you may encounter challenges due to limitations in supported data types and column sizes. Let's take the example of a City table with a Location column holding geography data, which needs to be converted to a varbinary type during loading since Azure Synapse doesn't natively support geography types. Example: 1. Convert to varbinary: During loading, convert the geography data to varbinary. 2. Data Chunking: Since PolyBase supports varbinary up to 8000 bytes, data may get truncated. To overcome this, split the data into manageable chunks. 3. Temporary Staging: Create a temporary staging table for the Location column. 4. Chunk Processing: Split the location data into 8000-byte chunks for each city, resulting in 1 to N rows for each city. 5. Reassembly: Reassemble the chunks using T-SQL PIVOT operator to convert rows into colum...

Incremental Data Loading from Databases for ETL

  pexel Let first discuss what is incremental loading into the data warehouse by ETL from different data sources including databases. Incremental Loading into Data Warehouses: Incremental loading is crucial for efficiently updating data warehouses without reprocessing all data. It involves adding only new or modified data since the last update. Key aspects include: 1. Efficiency: Incremental loading reduces processing time and resource usage by only handling changes. 2. Change Detection: Techniques like timestamp comparison or change data capture (CDC) identify modified data. 3. Data Consistency: Ensure consistency by maintaining referential integrity during incremental updates. 4. Performance: Proper indexing, partitioning, and parallel processing enhance performance during incremental loads. 5. Logging and Auditing: Logging changes ensures traceability and facilitates error recovery in incremental loading processes. Incremental Loading Explained In contrast to a full load,...