This challenge is all about identifying sequences of characters in a string using a SET based query. The task is to identify the longest sequence of characters within a given string.

The challenge will be to find each intersection of membership date ranges for each person and produce for this each unique range.

This challenge involves generating an organizational hierarchy and calculating the total orders created by each employee and his/her subordinates. It involves a number of challenges such as generating a resultset in the correct hierarchical form, calculating the orders created by each employee and his/her subordinates and finally calculating the total orders created by self and all the subordinates.

This challenge involves reading the audit log entries generated by a monitoring application and create a report that shows the up-time and down-time of a system that the application is monitoring.

This challenge presents a tough task of reorganizing the data in a sales table. The table is not normalized correctly and the sales detail data of three items are stored in each row. Your job is to reorganize the items in the table by sales amount (quantity * price). Reorganize the items from left to right, bottom to top. The item with the highest sales amount should come on top left of each invoice.

This is a challenge to identify the downtime of servers from the log data generated by a monitoring application. There is a monitoring application that keeps checking the status of several servers at 5 minute intervals. When the monitoring application finds that a particular server is down, it adds a record into the log table.

This challenge involves writing a logic to change the column position of values in the output based on the presence and absence of other values on each output row.

Here is an interesting challenge which might give you a fun time categorizing products by color. The first part of your job is to identify the unique color combinations of products and the second part is to identify the products that have the given color combination.

Several technicians are sent to a customer premises to do a certain maintenance work. Your task is to process the activity log entered by each technician and identify overlaps in the time sheet.

A table contains the list of modifications made to each card. Your job is to write a query that shows the first number, current number (most recent) and the number of changes made.

A SQL Server instance is set up to log the session start time and end time into a table. Given this table, your job is to find all time intervals in which no one is logged in. For the intervals separated by these empty intervals show the maximum number of simultaneous users.