SQL

What is Indexing? Indexing is a data structure technique that allows the database to quickly locate and access specific data. It’s similar to the index at the back of a book, which helps you find specific pages quickly. How Indexing Works Index Creation: The…

Spark SQL Operators Cheatsheet 1. Arithmetic Operators OperatorSyntaxDescriptionExample+a + bAdds two valuesSELECT 5 + 3;-a – bSubtracts one value from anotherSELECT 5 – 3;*a * bMultiplies two valuesSELECT 5 * 3;/a / bDivides one value by anotherSELECT 6 / 2;%a %…

For Better understanding on Spark SQL windows Function and Best Usecases do refer our post Window functions in Oracle Pl/Sql and Hive explained and compared with examples. Window functions in Spark SQL are powerful tools that allow you to perform calculations across a…

Here’s an enhanced Spark SQL cheatsheet with additional details, covering join types, union types, and set operations like EXCEPT and INTERSECT, along with options for table management (DDL operations like UPDATE, INSERT, DELETE, etc.). This comprehensive sheet…

Here’s a categorized Spark SQL function reference, which organizes common Spark SQL functions by functionality. This can help with selecting the right function based on the operation you want to perform. 1. Aggregate Functions FunctionDescriptionExampleavg()Calculates…

Data Definition Language (DDL) – to define and modify the structure of a database. Data Manipulation Language (DML) – to access, manipulate, and modify data in a database. Data Control Language (DCL) – to control user access to the data in the database…

Partitioning in SQL, HiveQL, and Spark SQL is a technique used to divide large tables into smaller, more manageable pieces or partitions. These partitions are based on a column (or multiple columns) and help improve query performance, especially when dealing with…

SQL query flows through the Oracle engine in the following steps: Step 1: Parsing The SQL query is parsed to check syntax and semantics. The parser breaks the query into smaller components, such as keywords, identifiers, and literals. Step 2: Optimization The parsed…

Let’s list all possible places where subqueries in MySQL or Hive QL or Pyspark SQL Query can be used: 1. In the SELECT Clause Subqueries can compute a value for each row. SELECT employee_id, (SELECT COUNT(*) FROM project_assignments pa WHERE pa.employee_id =…

Spark SQL supports several types of joins, each suited to different use cases. Below is a detailed explanation of each join type, including syntax examples and comparisons. Types of Joins in Spark SQL Inner Join Left (Outer) Join Right (Outer) Join Full (Outer) Join…

Temporary functions allow users to define functions that are session-specific and used to encapsulate reusable logic within a database session. While both PL/SQL and Spark SQL support the concept of user-defined functions, their implementation and usage differ…

Window functions, also known as analytic functions, perform calculations across a set of table rows that are somehow related to the current row. This is different from regular aggregate functions, which aggregate results for the entire set of rows. Both Oracle PL/SQL…

Indexing in SQL is a technique used to improve the performance of queries by creating special data structures (indexes) that allow for faster data retrieval. Indexes are created on one or more columns of a table, and they store the values of those columns in a sorted…

LIKE Operator: The LIKE operator is used to search for a specified pattern in a column. It allows the use of wildcards: % (percent sign): Matches zero or more characters. _ (underscore): Matches any single character. Examples: SELECT * FROM employees WHERE last_name…

Normalization and denormalization are two opposing database design techniques aimed at achieving different goals. Let’s explore each concept: Normalization: Normalization is the process of organizing the data in a database to minimize redundancy and dependency….

Designing a well-structured and efficient database schema in SQL involves several steps and considerations. Here’s a comprehensive guide to help you design a database schema that meets your application requirements while ensuring efficiency, scalability, and…

Optimizing SQL performance is crucial for ensuring that database operations are efficient and scalable. Here are some steps you can take to optimize SQL performance: Indexing: Proper indexing can significantly improve query performance. Identify columns frequently…