Question

我有一个名为batch

的表格

batch_id      unit_size       product_id
2             100000          c001
3             30000           t008

另一个名为batch_process

的表

batch_id      process_id      status
2             100000          0
2             100000          1
2             100000          2
2             100000          1
3             30000           2
3             30000           2
3             30000           2
3             30000           2

现在我想获得输出3 AS batch_id表单batch表格，因为在batch_process表中，process_id状态2的{{1}}状态为batch_id = 3 {1}}

如何选择它。

Answer 1

此查询可能会帮助您

SELECT batch1.batch_id,batch_process1.process_id 
FROM batch_process AS batch_process1,
batch AS batch1
WHERE batch1.batch_id = batch_process1.batch_id 
AND batch_process1.status=2

Answer 2

如果您只想选择状态为2的batch_id，那么您只需编写：

select distinct batch_id from batch_process where status=2

但是如果你想从批处理表中查询信息，不仅要查询batch_id，你可以写：

SELECT batch.batch_id,
       batch.unit_size,
       batch.product_id
LEFT JOIN batch_process ON batch.batch_id=batch_process.batch_id
WHERE batch_process.status=2

遇到mysql问题选择查询

2 个答案: