mysql查询中的左连接问题

Question

我有一个问题

SELECT DISTINCT c.camp_id AS camp_id,
                c.camp_key AS camp_key,
                c.camp_active AS camp_active,
                c.camp_deleted AS camp_deleted,
                c.camp_name AS camp_name,
                c.camp_cpc AS camp_cpc,
                c.camp_destination AS camp_destination,
                camp_token1,
                camp_token2,
                camp_token3,
                camp_token4,
                camp_token5,
                camp_token6,
                camp_token7,
                camp_token8,
                camp_token9,
                camp_token10,
                token1_field,
                token2_field,
                token3_field,
                token4_field,
                token5_field,
                token6_field,
                token7_field,
                token8_field,
                token9_field,
                token10_field,
                group_name,
                group_id,
                source_id,
                source_name,
                user_name
                FROM mt_campaigns c
                LEFT JOIN mt_offers USING (camp_id)
                LEFT JOIN mt_groups USING (group_id)
                LEFT JOIN mt_traffic_sources USING (source_id)
                LEFT JOIN mt_account WHERE c.owner_id = mt_account.user_id
                WHERE camp_deleted=0

现在我想连接另一个表(Mt_account)，它有一个名为user_id的列，它与mt_canpaigns的owner_id列相匹配。

如何编辑联接查询？

Answer 1

替换

LEFT JOIN mt_account WHERE c.owner_id=mt_account.user_id

为

LEFT JOIN mt_account ON c.owner_id=mt_account.user_id

您需要使用ON而不是WHERE来定义要连接的字段