6. What’s the difference between UNION and JOIN? A. UNION combines rows from two tables into a single result set, keeping all duplicates; JOIN combines the results of two queries based on a related column.B. UNION can only be used with SELECT statements; JOIN can be used with any SQL statementC. UNION is used to combine columns from two tables; JOIN is used to combine rows from two tablesD. UNION combines the results of two queries into a single result set, removing duplicates; JOIN combines columns from two or more tables based on a related column.
Question
6. What’s the difference between UNION and JOIN? A. UNION combines rows from two tables into a single result set, keeping all duplicates; JOIN combines the results of two queries based on a related column.B. UNION can only be used with SELECT statements; JOIN can be used with any SQL statementC. UNION is used to combine columns from two tables; JOIN is used to combine rows from two tablesD. UNION combines the results of two queries into a single result set, removing duplicates; JOIN combines columns from two or more tables based on a related column.
Solution
The difference between UNION and JOIN in SQL is as follows:
A. UNION is used to combine the results of two or more SELECT statements without returning any duplicate rows. To use UNION, each SELECT statement within the UNION must have the same number of columns with similar data types. The columns in each SELECT statement must also be in the same order. The result of UNION is a single result set that includes all the rows from both SELECT statements, excluding duplicates.
On the other hand, JOIN is used to combine rows from two or more tables based on a related column between them. This allows you to query data from multiple tables as if they were a single table. There are several types of JOIN operations, including INNER JOIN, LEFT JOIN, RIGHT JOIN, and FULL JOIN.
B. The statement that UNION can only be used with SELECT statements is correct. UNION is specifically designed to combine the results of two or more SELECT statements. JOIN, however, is not limited to SELECT statements and can be used with other SQL statements.
C. The statement that UNION is used to combine columns from two tables is incorrect. UNION is used to combine rows from two or more SELECT statements, not columns. JOIN, on the other hand, is used to combine rows from two or more tables based on a related column.
D. As mentioned earlier, UNION combines the results of two or more SELECT statements into a single result set, removing duplicates. JOIN combines columns from two or more tables based on a related column.
Similar Questions
A UNION query is which of the following?Combines the output from multiple queries and must include the same number of columns.Combines the output from no more than two queries and must include the same number of columns.Combines the output from multiple queries and does not include the same number of columns.Combines the output from no more than two queries and does not include the same number of columns.
The UNION of two tablesa.is a table containing all rows that are in the first table but not in the second table.b.is a table containing all rows that are in the second table but not in the first table.c.is a table containing all rows that are in either table or both.d.is a table containing all rows that are common to both tables.
In which scenario would using UNION ALL be preferable over UNION in SQL?Question 16Answera.When you want to filter out NULL values from the result setb.When you want to sort the combined result set based on a specific columnc.When you want to eliminate duplicate rows from the combined result setd.When you want to merge result sets while preserving duplicate rows
Select the correct answerWhat is the purpose of the SQL UNION operator?OptionsCombines rows from two or more tables, removing duplicatesCombines rows from two or more tables, including duplicatesSorts rows in a tableDeletes rows from a table
What does the UNION operation automatically eliminate in SQL?
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