Which of the following are best practices for queries containing table joins?Select THREE correct answers.A. Join only tables that are really required and used (e.g. in SELECT)B. Filter tables within JOIN instead of within WHEREC. Filter tables within WHERE instead of within JOIND. Use EXISTS when you want to combine columns from two tablesE. Apply a proper filter so that only relevant records are processed
Question
Which of the following are best practices for queries containing table joins?Select THREE correct answers.A. Join only tables that are really required and used (e.g. in SELECT)B. Filter tables within JOIN instead of within WHEREC. Filter tables within WHERE instead of within JOIND. Use EXISTS when you want to combine columns from two tablesE. Apply a proper filter so that only relevant records are processed
Solution
The correct answers are:
A. Join only tables that are really required and used (e.g. in SELECT) This is a best practice because it reduces the amount of data that needs to be processed, which can significantly improve performance.
C. Filter tables within WHERE instead of within JOIN Filtering tables within the WHERE clause can often be more efficient than filtering within the JOIN clause. This is because the WHERE clause is processed after the JOIN clause, so it can reduce the amount of data that needs to be processed in the JOIN.
E. Apply a proper filter so that only relevant records are processed This is a best practice because it reduces the amount of data that needs to be processed, which can significantly improve performance. It also helps to ensure that the results of the query are accurate and relevant.
Similar Questions
Generally, WHERE EXISTS:Select TWO correct answers.A. is more performant than JOINB. is less performant than JOINC. is interchangeable with JOIND. should be used instead of JOIN for filtering purposes solely
In which cases would you use an outer join?Select one:a.The tables being joined have only matched data.b.Only when the tables have a primary key/foreign key relationship.c.The tables being joined have only unmatched data.d.The tables being joined have both matched and unmatched data.e.The tables being joined have NOT NULL columns.
Which of the following is one of the basic approaches for joining tables?SubqueriesNatural joinUnion JoinDAll of the above
Table A and Table B are to be joined in a query.Which type of join will include all rows from tables A and B in the result?
Which statements are true regarding the USING and ON clauses in table joins? Select one or more:a.The WHERE clause can be used to apply additional conditions in SELECT statement containing the ON or the USING clause.b.Both USING and ON clause can be used for equijoins and nonequijoins c.Maximum of one pair of columns can be joined between two tables using the ON claused.The ON clause can be used to join tables on columns that have different names but compatible data types.
Upgrade your grade with Knowee
Get personalized homework help. Review tough concepts in more detail, or go deeper into your topic by exploring other relevant questions.