Explain the difference between INNER JOIN, LEFT JOIN, and RIGHT JOIN with examples. When would you use each?
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You know that you have a lot of old data in the Departments table, and many of the department names are no longer used-meaning that no employee rows are matched to these old department rows. Which is the best join to use if I want a list of Departments where there are no Employees related (matched) to those departments? Select the best answer from the following. The inner join will produce the result set needed. You must use a self-join to produce the result set needed. You can use either the left or right join to produce the result set needed. You will have to query each table individually and match the results in Excel to answer the question. QUESTION 5 You have a table called Employees. For each employee there is a ManagerID column. This column provides the employee number (also from the same Employees table) of the person who is the manager for the employee selected. If you wish to create a query that will show each employee and then their manager (remember the manager is simply an employee in the same table) which is the best join to use? Select the best answer from the following. The inner join will produce the result set needed, but you must create a separate Managers table first. This is an example of a self-join. This type of query is not supported in Microsoft SQL Server. You will have to change the design of your database first. You must create two separate queries and then manually join the results together.
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27. MySQL: Joins Which expression is not correct? Pick one option. MySQL joins are used to join rows from two or more tables based on the associated column between them. The INNER JOIN keyword selects records that have matching values in both tables. Using the RIGHT JOIN keyword returns only records that are joined in the right way. 28. MySQL FOREIGN KEY Constraint Which expression is not correct? Pick one option. A column might have a foreign key reference to itself. MySQL supports foreign key references between one column and another within a table. Corresponding columns in the foreign key and the referenced key must have similar data types. None of the above, all expressions are correct.
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10. Suppose you want to create a query that displays the class name, customer’s last name, instructor’s last name, and class date. What type of JOIN should you use for linking the tables together?
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