The provided link is a resource from W3Schools explaining the SQL UNION operator. The UNION operator combines the result sets of two or more SELECT statements, with specific requirements:

1. Each SELECT statement within the UNION must have the same number of columns and these columns must have similar data types.
2. The columns in every SELECT statement must also be in the same order.
3. The UNION operator selects only values by default. To allow duplicate values, you use UNION ALL.

The page demonstrates the usage of the SQL UNION operator with examples, showcasing its application for retrieving distinct values from multiple tables as well as selecting duplicate values. also illustrates using the SQL UNION with WHERE clause and provides an example with an alias.

The SQL UNION operator comes with a few exception cases and considerations to keep in mind:

1. Data Type and Order: As mentioned earlier, when using the UNION operator, the SELECT statements must have the same number of columns with similar data types. The columns in each SELECT statement also need to be in the same order.

2. Handling Duplicate Records: By default, the UNION operator eliminates duplicate records from the final result. If you want to retain duplicate records, you can use the UNION ALL operator instead of just UNION.

3. Aliases: When using the UNION operator, you might want to assign aliases to the columns in the result set for better readability. This can be done using the AS keyword followed by the alias name.

4. WHERE Clause: It's important to note that when using the UNION operator with a WHERE clause in each SELECT statement, the conditions apply to the individual SELECT statements and not to the final result set. If you want to apply conditions to the final result set, you would use the WHERE clause outside the individual SELECT statements.

5. Aggregate Functions: When using the UNION operator, the result sets must contain the same aggregate functions in order to combine the results effectively.

These exceptions and considerations are essential for effectively utilizing the SQL UNION operator and ensuring proper functionality when combining result sets from multiple SELECT statements.

Certainly! Here are a few examples illustrating the usage of the SQL UNION operator:

Example 1: Retrieving Distinct Values

SELECT column1, column2
FROM table1
UNION
SELECT column1,2
FROM table2;

In this example, the UNION operator combines the results of two SELECT statements from two different tables, returning only distinct values.

Example 2: Retrieving All Values (including duplicates)

SELECT column1,2
FROM table1
UNION ALL
SELECT column1, column2
FROM table2;

Here, UNION ALL operator is used to combine the results of two SELECT statements, including duplicate values in the final result.

Example 3: Using Aliases

SELECT column1 AS col1_alias column2 AS col2_alias
FROM table1
UNION
SELECT column3 col1_alias, column4 AS col2_alias
FROM table2;

In example, aliases are assigned to the columns in the result set for better readability.

These examples demonstrate the versatility of the SQL UNION operator in combining result sets from multiple SELECT statements

The SQL UNION operator is commonly used in various practical scenarios in management and data analysis. Here are some practical work scenarios where the UNION operator is frequently employed:

1. Combining Data from Similar Tables: When working with databases that have similar structures, such as multiple tables with identical or compatible columns, the UNION operator can be used to consolidate data from these tables into a single result set for reporting or analysis.

2. Merging Results from Similar Queries: In scenarios where similar queries need to be performed on different subsets of data, the UNION operator allows for merging the results of these queries into a unified set.

3. Reporting and Analysis: In the context of data analysis and reporting, the UNION operator can be utilized to combine data from different sources or time periods, facilitating comprehensive analysis and across various dimensions.

4. Implementing Dynamic Search Functionality: The UNION operator can support dynamic search functionality where the results from multiple search queries on related database tables or columns are combined and presented to users for a comprehensive view.

5. Handling Multiple Criteria Scenarios: When dealing with complex search or filtering scenarios, the UNION operator can help in combining results that meet different criteria or conditions from various tables.

6. Data Normalization and Cleansing: In cases where data from different sources or tables needs to normalized or cleansed, the UNION operator can assist in consolidating and standardizing the data for further processing.

These practical work scenarios demonstrate the versatile use of the UNION operator in SQL for combining, analyzing, and presenting data from multiple sources or.

I understand. Let's consider a practical example.

Suppose you are working with a company database. The company has two separate tables for sales data - one for online sales and another for in-store sales. Each table has the same structure (columns) storing information such as sales date, customer details, and the amount of the sale.

Now, if you need generate a report that combines both online and in-store sales data get a comprehensive view of all sales, you can use the UNION operator to merge the results of separate queries on these two tables into a single dataset.

In this scenario, the UNION operator allows you to consolidate the sales data from both sources and a comprehensive report showing the total sales across all channels.

This demonstrates the practical use of the UNION operator in combining result from multiple tables to gain valuable insights and make informed business decisions.

If you have further questions or need more details, feel free to ask!

Certainly! Here are a few more real-life scenarios to illustrate the practical use of the UNION operator:

1. HR Data Management: Suppose a company has separate tables for full-time employees' data and part-time employees' data. Using the UNION operator, HR can consolidate the employee information from both tables for comprehensive reporting, such as total headcount and employee demographics, regardless of their employment type.

2. E-commerce Website Analytics: In an e-commerce setting, the website might have separate tables for tracking customer orders from the website and from the mobile app. By using the UNION operator, the marketing team could generate a single report on total sales and customer behavior across both platforms.

3. Inventory Management: A retail business may have separate tables for tracking inventory in different warehouses. By employing the UNION operator, the operations team can merge the inventory data from all warehouses into one comprehensive view to optimize supply chain management.

4. Academic Institution Course Data: An academic institution might have separate tables for undergraduate and postgraduate course enrollment. The administration can use the UNION operator to merge this data for efficient resource planning and academic analysis.

5. Financial Transactions: A bank could have separate tables for ATM transactions and online banking transactions. By using the UNION operator, the bank can create a consolidated report for regulatory compliance and risk management, showing a comprehensive view of all transactions.

In each of these scenarios, the UNION operator is used to consolidate and analyze data from multiple sources for comprehensive reporting and informed decision-making.

If you have further inquiries or need more examples, feel free to ask!