Status
Done

INTRODUCTION
The UNION operator in MySQL is a powerful tool for combining the results of multiple SELECT statements into a single result set. It's particularly useful when you want to retrieve data from different tables or different parts of the same table that share a similar structure.
Key Points:
- Combines Results: UNION merges the output from two or more SELECT queries.
 - Removes Duplicates (Default): By default, UNION eliminates duplicate rows from the combined result set. This ensures you only get unique data points.
 - Matching Columns: The SELECT statements used with UNION must have the same number of columns in the same order, and the data types of corresponding columns must be compatible.
 - Column Names: The column names in the final result set are inherited from the 
firstSELECT statement in the UNION chain. - The key difference between 
UNION ALLandUNIONis that UNION ALL retains duplicate rows in its output, while UNION automatically removes them. 
Syntax:
SELECT 
  column1, 
  column2, 
FROM 
    table_name 
UNION 
     SELECT 
          column1, 
          column2, 
       FROM 
          table_name SELECT...: This represents the individual SELECT statements that retrieve data.FROMtable1, table2, table3: These are the tables from which data is fetched.UNION: This keyword combines the results from the precedingSELECTstatements, removing duplicates (default behavior).
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MySQL UNION operator
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MySQL UNION vs JOIN
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OUTPUT OF UNION AND JOIN
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MySQL UNION and column alias examples
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