Databases / SQL
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Databases / SQL / Backup and Recovery (19)
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Databases / SQL / SQL Queries (13)
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Given a table with two columns, this SQL query will find the most common value in the second column.
About this solution: The candidate's solution is complete and solves the problem. The approach is straightforward and uses a single query to find the most common value in the second column.
Write a SQL query to find all pairs of rows in a table where the values in the two columns are within 10% of each other.
About this solution: This solution is correct and demonstrates a level of completeness. It solves the problem and uses the correct SQL syntax. The approach is straightforward and easy to understand.
This technical problem deals with writing a function that can take in a database name and table name, and return the number of rows in the table.
About this solution: The candidate's solution is complete and solves the problem. The candidate's approach is to use the COUNT() function, which is an optimal way to count the number of rows in a table.
This technical problem involves writing a SQL query to find the average price of all products in a database. An example product table is provided, and the expected output is the average price of all products in the table.
About this solution: This solution is complete and solves the problem. The approach is straightforward and easy to understand.
This technical problem describes how to write a SQL trigger that will automatically update the "last_updated" column whenever a change is made to any of the other columns in a table. The example input table contains employee data, and the example output shows how the "last_updated" column would be updated after a change is made to one of the other columns.
About this solution: The candidate's solution is correct and demonstrates a good understanding of how to write a SQL trigger.
This technical problem involves writing a SQL query to find users with multiple orders. The example input and output are provided.
About this solution: The solution is correct and demonstrates a level of completeness. The approach is straightforward and easy to follow.
Given two tables, this SQL query finds all customers who have at least one order in each table.
About this solution: The solution above is optimal because it uses the IN operator to check if the customer_id from table1 is in table2.
The goal is to find the number of unique users in a table. The table has the following columns: user_id, name. The query should return the number of unique users. In the example above, the answer would be 3.
About this solution: The candidate's solution is correct and uses an efficient method to count the number of unique users.