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We have taken two aliases (a, b) for the same table (Activity). To calculate the average time the process takes to complete, we need to calculate the difference
We have taken two aliases (a, b) for the same table (Activity). To calculate the average time the process takes to complete, we need to calculate the difference between the end time and the start time of each process. Therefore, we use the condition a.activity_type=\'start\' and b.activity_type=\'end\'. By calculating b.timestamp - a.timestamp, we get the time taken to complete the process.\n\nWe also use the condition a.machine_id = b.machine_id because a process that starts on a specific machine also ends on the same machine. Similarly, the process_id must be the same for both the start and end activities to ensure we are calculating the duration for the same process.\n\nThe final query groups the results by machine_id and calculates the average processing time for each machine, rounding the average to three decimal places for readability.\n\nFeel free to let me know if you need any further adjustments or additional details.\n\n# Code\n```\n# Write your MySQL query statement below\nSELECT a.machine_id, ROUND(AVG(b.timestamp-a.timestamp),3) AS processing_time\nFROM Activity a,Activity b\nWHERE a.activity_type=\'start\' and b.activity_type=\'end\' and a.process_id=b.process_id and a.machine_id=b.machine_id\nGROUP BY a.machine_id;\n```
['MySQL']