SQL查询未返回预期结果求助：员工操作数据表分析

Let's work through this step by step to figure out why your query isn't returning the results you expect. First, let's make your sample data easier to read, then go over what we need to dig into the problem:

Sample Data (Formatted) #

Here's your dataset organized into a clear table:

What We Need to Know to Help Fix This #

To zero in on the issue, please share:

• Your actual SQL query: Paste it here wrapped in backticks (`) so we can parse its logic—are you using joins, filters, aggregations, or window functions?
• Your expected outcome: What were you hoping to get? For example, are you trying to link 'P'/'D' events to the most recent 'R' event's block_id, count events per type, or something else?
• Current incorrect results: Is the query missing rows, showing wrong counts, returning unexpected block_id values, or throwing an error?

Quick Checks to Try In the Meantime #

While we wait for those details, here are some common pitfalls that might be causing issues with this dataset:

• NULL block_id handling: Most 'P' and 'D' rows have empty block_id—if your query filters for block_id IS NOT NULL, you'll accidentally exclude those rows.
• Timestamp-based associations: If you're trying to tie 'P'/'D' events to the preceding 'R' event, you might need window functions like LAG() or LAST_VALUE() with proper partitioning (PARTITION BY EmpID) and ordering (ORDER BY timestamp).
• Duplicate row impact: You have multiple identical 'P' rows with the same timestamp—if you're aggregating without DISTINCT, you might be overcounting events.

Once you share the query and expected results, we can dive into a precise fix!

内容的提问来源于stack exchange，提问作者Anjali