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Write a SQL query to find all pairs of rows (a, b) such that a is in table A, b is in table B, and a and b have the same value for column C.

About this solution: This solution is correct and demonstrates a good understanding of SQL. The approach is straightforward and easy to follow.

This technical problem deals with finding pairs of records from two tables that have the same value for a common column.

About this solution: The solution above is optimal because it uses an inner join to find the records that have the same value for column C.

This technical problem involves writing a SQL query to find the average salary of employees by department. The example input table includes columns for department, first name, last name, and salary. The expected output is a table with columns for department and average salary.

About this solution: This solution is complete and solves the problem. The approach is straightforward and easy to follow.

Given two tables, "A" and "B", write a SQL query to find all the rows from table "A" that have no corresponding rows in table "B".

About this solution: The candidate's solution is correct and demonstrates a good understanding of SQL. The approach is sound and the solution is complete.