✔️✔️ Very Easy Approach Using JOIN || Simple and Clear Query Explanation ❕❕❕
Query Breakdown\n\n### 1. Select Columns:\n\nselect a1.machine_id, round(avg(a2.timestamp-a1.timestamp), 3) as processing_time\n\nWe want to select the machine_
# Query Breakdown\n\n### 1. Select Columns:\n```\nselect a1.machine_id, round(avg(a2.timestamp-a1.timestamp), 3) as processing_time\n```\nWe want to select the **machine_id** and the average processing time, rounded to 3 decimal places.\n\n### 2. From Activity Table:\n```\nfrom Activity a1\n```\nWe start with the **Activity** table and refer to it as **a1**.\n\n### 3. Join with Activity Table Again:\n```\njoin Activity a2\non a1.machine_id = a2.machine_id and a1.process_id = a2.process_id\nand a1.activity_type = \'start\' and a2.activity_type = \'end\'\n```\nThe join conditions ensure that:\n- **machine_id** in **a1** matches **machine_id** in **a2**.\n- **process_id** in **a1** matches **process_id** in **a2**.\n- The activity in **a1** is of type **\'start\'** and in **a2** is of type **\'end\'**.\n\n### Group By Machine ID:\n```\ngroup by a1.machine_id\n```\nWe group the results by **machine_id** to calculate the average processing time for each machine.\n\n# Full Query\n```\n# Write your MySQL query statement below\nselect a1.machine_id, round(avg(a2.timestamp-a1.timestamp), 3) as processing_time \nfrom Activity a1\njoin Activity a2 \non a1.machine_id=a2.machine_id and a1.process_id=a2.process_id\nand a1.activity_type=\'start\' and a2.activity_type=\'end\'\ngroup by a1.machine_id\n```
['MySQL']