我对将结果放入两个表有点困惑，我知道这很简单，但没有任何线索。。这是我的查询，它给了我结果，但当我使用group by时，它只给了我一行的结果，即使数据库中的实际结果是（300500），因为我是通过lead_id获取结果的，这在两个表中都很常见。。
SELECT inv.amount, crmd.computers, crmd.product_id, crmd.pc_opti
FROM invoice AS inv, lead_crm_data AS crmd
WHERE inv.lead_id = '310'
AND crmd.lead_id = '310'
GROUP BY inv.lead_id
这是给定查询的结果。。
amount computers product_id pc_opti
300 2 7, 6 2
300 3 7, 6 3
540 2 7, 6 2
540 3 7, 6 3
GROUP BY的结果
300 2 7, 6 2
所需结果
300 2 7, 6 2
540 3 7, 6 3
试试这个：
SELECT inv.amount, crmd.computers, crmd.product_id, crmd.pc_opti
FROM invoice AS inv, lead_crm_data AS crmd
WHERE inv.lead_id = '310'
AND crmd.lead_id = '310'
GROUP BY inv.amount
您可以使用更好的（IMHO）语法：
SELECT inv.amount, crmd.computers, crmd.product_id, crmd.pc_opti
FROM invoice AS inv INNER JOIN lead_crm_data AS crmd
ON inv.lead_id = crmd.lead_id
AND inv.lead_id = '310'
GROUP BY inv.amount