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表A:qa_invoicesMySQL的左连接复制
invoice_code invoice_date
1 25
2 25
3 26
4 27
表B:qa_invoicesitems
invoice_code item_quantity item_name
1 2 Mouse
1 1 CPU
2 5 Keyboard
3 1 Router
4 3 Switch
我的查询:
SELECT SUM(qa_invoicesitems.item_quantity) AS item_count, COUNT(*) AS invoice_count
FROM qa_invoices
LEFT OUTER JOIN qa_invoicesitems USING (invoice_code)
WHERE qa_invoices.invoice_date = 25
我的结果:
item_count invoice_count
8 3
我有几个小时寻找解决方案,问题是要统计发票(invoice_count)。
正确的结果将是:
item_count invoice_count
8 2
如果有人能帮助我与我的poblem。
哇,快速有效。非常感谢 –