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Part IV: Modifying Data with SQL

  Inserting Records · Updating Records · Deleting Records Modifying data—adding new rows, updating existing ones, and removing obsolete entries—is the flip side of querying. Without the ability to change data, databases become static archives. In this detailed guide, you’ll learn step by step how to insert, update, and delete records safely and efficiently in a relational database. Inserting Records Every database starts empty. The INSERT statement populates tables with new rows. You’ll discover how to add single records, bulk load data from other queries, and handle conflicts or defaults. 1. Single-Row Inserts Use INSERT INTO … VALUES to add one row at a time. Always specify the column list to avoid mismatches when the schema changes. sql INSERT INTO employees (first_name, last_name, email, hire_date, salary) VALUES ('Jane', 'Doe', 'jane.doe@example.com', '2025-08-15', 60000); Key points: Match the order of columns and values exactly. Omit columns wit...
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Lesson 5.5 – Basic Statistics (AVERAGE, MEDIAN, MODE)

Lesson 5.5 – Basic Statistics (AVERAGE, MEDIAN, MODE) Basic statistical functions help you understand the central tendency of your data. Excel provides simple functions to calculate the average value, the middle value, and the most frequent value in a dataset. These functions are widely used in business, finance, education, and data analysis. 1. What Are Basic Statistics? Basic statistics summarize your data and help you understand its general behavior. The three most common measures are: AVERAGE – The arithmetic mean MEDIAN – The middle value MODE – The most frequent value These functions are essential for analyzing trends, comparing groups, and making decisions. 2. AVERAGE Function The AVERAGE function calculates the mean of a group of numbers. Syntax: =AVERAGE(range) Example: =AVERAGE(B2:B10) Use AVERAGE when you want a general idea of the typical value in your dataset. 3. MEDIAN Function The MEDIAN functio...
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Lesson 5.4 – Sorting and Filtering for Analysis

Lesson 5.4 – Sorting and Filtering for Analysis Sorting and filtering are essential tools for analyzing data in Excel. They help you focus on the information that matters, identify patterns, and prepare your dataset for deeper analysis using charts or PivotTables. In this lesson, you will learn how to sort and filter data specifically for analytical purposes. 1. Why Sorting and Filtering Matter in Analysis When working with large datasets, it is difficult to understand trends or find insights by looking at raw numbers. Sorting and filtering allow you to: Identify top or bottom values Focus on specific categories Analyze trends over time Prepare clean data for charts and PivotTables These tools are the foundation of any data‑driven workflow. 2. Sorting for Analysis Sorting helps you reorganize your data to reveal patterns. • Sorting Numbers Examples: Sort sales from highest to lowest Sort expenses from smallest to largest ...
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Lesson 5.3 – Introduction to PivotTables

Lesson 5.3 – Introduction to PivotTables PivotTables are one of the most powerful tools in Excel. They allow you to summarize, analyze, and explore large datasets quickly — without writing formulas. With just a few clicks, you can transform raw data into meaningful insights. 1. What Is a PivotTable? A PivotTable is an interactive table that summarizes data. It helps you answer questions such as: How many sales did each product generate? Which month had the highest revenue? How many orders came from each region? What is the average value per category? PivotTables are essential in business, finance, marketing, and reporting. 2. Requirements for a Good PivotTable Before creating a PivotTable, your data should: Be organized in a clean table format Have clear column headers Contain no blank rows Use consistent data types (numbers, dates, text) Using an Excel Table is recommended for best results. 3. How to Create...
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Lesson 5.2 – Quick Analysis Tool

Lesson 5.2 – Quick Analysis Tool The Quick Analysis Tool is one of Excel’s most powerful features for beginners. It allows you to instantly apply formatting, create charts, add totals, and perform basic analysis with just one click. This tool helps you understand your data faster and make quick decisions without navigating multiple menus. 1. What Is the Quick Analysis Tool? The Quick Analysis Tool appears automatically when you select a range of data. It provides a small menu with shortcuts to the most common analysis features, including: Formatting – Data bars, color scales, icon sets Charts – Column, line, pie, and more Totals – Sum, average, count, running totals Tables – Convert data into an Excel Table Sparklines – Mini‑charts inside cells This tool is perfect for quick insights and fast visualizations. 2. How to Use the Quick Analysis Tool Steps: Select a range of data (at least two rows or columns). Look for the ...
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Lesson 5.1 – Basic Charts

Lesson 5.1 – Basic Charts Charts are one of the most effective ways to visualize data in Excel. They help you understand trends, compare values, and communicate information clearly. In this lesson, you will learn how to create the three most common chart types used worldwide: column charts, line charts, and pie charts. 1. Why Charts Matter Charts transform raw numbers into visual insights. They make it easier to: Identify patterns and trends Compare categories or time periods Highlight important values Present data in a professional way Charts are essential in business reports, presentations, dashboards, and data analysis. 2. How to Create a Chart Steps: Select the data you want to visualize (including headers). Go to Insert on the Ribbon. Choose the chart type you want to create. Excel will generate the chart automatically and place it on your worksheet. 3. Column Charts Column charts are used to compare values...
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