Combine Two Tables into a Single Table and Eliminate Duplicate Rows

C.

The correct answer is C. Use the UNION operator in SQL to combine the tables.

Explanation: To combine two tables in an ANSI-SQL compliant database with identical columns, you can use the UNION operator. The UNION operator combines the result sets of two SELECT statements into a single result set, eliminating duplicate rows.

Syntax:

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SELECT column1, column2, ...  FROM table1  UNION  SELECT column1, column2, ...  FROM table2; 

In this case, since the two tables have identical columns, the SELECT statements for both tables will be the same. Here's an example:

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SELECT column1, column2, ...  FROM table1  UNION  SELECT column1, column2, ...  FROM table2; 

This will combine the rows from table1 and table2 into a single table, eliminating any duplicate rows. If you want to include duplicates in the result set, you can use the UNION ALL operator instead.

Option A, using the JOIN operator, will combine the two tables based on a common column or set of columns. This will not remove duplicate rows from the result set, as it will return all matching rows from both tables.

Option B, using nested WITH statements, is not a valid approach to combine tables.

Option D, using the UNION ALL operator, will combine the rows from table1 and table2 into a single table, including any duplicate rows.