Showing posts with the label Self-study Materials

Featured Post

SQL Query: 3 Methods for Calculating Cumulative SUM

SQL provides various constructs for calculating cumulative sums, offering flexibility and efficiency in data analysis. In this article, we explore three distinct SQL queries that facilitate the computation of cumulative sums. Each query leverages different SQL constructs to achieve the desired outcome, catering to diverse analytical needs and preferences. Using Window Functions (e.g., PostgreSQL, SQL Server, Oracle) SELECT id, value, SUM(value) OVER (ORDER BY id) AS cumulative_sum  FROM your_table; This query uses the SUM() window function with the OVER clause to calculate the cumulative sum of the value column ordered by the id column. Using Subqueries (e.g., MySQL, SQLite): SELECT, t1.value, SUM(t2.value) AS cumulative_sum FROM your_table t1 JOIN your_table t2 ON >= GROUP BY, t1.value ORDER BY; This query uses a self-join to calculate the cumulative sum. It joins the table with itself, matching rows where the id in the first table is greater than or

Hot Skills: Spark Self Study Materials

Spark: With job postings up 120% year-over-year on Dice, demand for this open-source cluster-computing framework is broad-based. Government contractors and financial-services firms are just a few of the groups eager to find candidates with this skillset. 2015 Average Salary: $113,214 Related: SPARK Self Study Materials Spark Big Data and Cloud:  As companies expand their tech infrastructures, they need cloud and Big Data services such as Azure (#2), Hive (#8), and Cassandra (#9) for data storage, analysis, and security. Big Data and cloud-related skills dominated the Highest-Paid Skills list on Dice’s salary survey for the second straight year.  2015 Average Salary: Big Data—$121,328 Azure — $110,207 Salesforce: This customer-service platform serves as the bedrock for many companies’ customer service departments. Demand for Salesforce professionals seems unlikely to decline anytime soon. Employers are even willing to offer telecommuting options to lure Salesforce talent. 2