mysql - 从两个表中选择数据，mysql

Question

我的数据库有两个表“客户”和“交易”。

客户表有 8 列，交易表有 4 列，

客户表主键是id，交易表没有主键，交易表中每个客户存在多条记录。

我需要从客户中选择 4 列，从交易中选择 3 列。

这里是查询:

query ='SELECT c.customer_id AS "Customer ID",
               c.father_name AS "Father Name",
               c.address AS Address,
               c.phone_number AS "Phone Number",
               c.mobile_number AS "Mobile Number",
               c.id_proof AS "ID Proof",
               c.area AS "Area",
               c.ip_address AS "IP Address",
               c.mac_address AS "MAC Address",
               c.package_type AS "Package Type",
               c.name AS Name,
               c.activation_date AS "Activation Date",
               c.status AS "Status",
               c.installation_cost AS "Installation Cost",
               c.totalamount_paid AS "Total Amount Paid",
               c.monthly_amount AS "Monthly Amount",
               c.lastpaid_date AS "Last Paid Date",
               c.lastpaid_amount AS "Last Paid Amount",
               c.nextpay_date AS "Next Pay Date",
               c.totaldue_amount AS "Total Due Amount",
               t.agent_id AS "Agent ID",
               t.token_number AS "Token Number",
               t.machine_id AS "Machine ID"
          FROM customer c INNER JOIN transaction t ON c.customer_id = t.customer_id
        WHERE DATE(t.paid_date)BETWEEN '" + fromDate + "'AND '" + toDate + "' ";

但问题是:

该记录在事务表中存在多少次，即其给出记录的次数，但我只需要一次。

我该怎么做？

Answer 1

... GROUP BY c.customer_id

您很可能想要对某些列进行求和或使用其他聚合函数。