Hour 15. Combining Multiple Queries into One

During this hour, you learn how to combine SQL queries into one by using the UNION, UNION ALL, INTERSECT, and EXCEPT operators. Once again, you must check your particular implementation for any variations in the use of the UNION, UNION ALL, INTERSECT, and EXCEPT operators.

The highlights of this hour include

  • An overview of the operators used to combine queries

  • When to use the commands to combine queries

  • Using the GROUP BY with the compound operators

  • Using the ORDER BY with the compound operators

  • How to retrieve accurate data

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