Question

我有一张员工的多个就业记录表，我想查询一定范围的日期。
参数为Company.id，date_hired，date_end
结果必须在指定日期的范围内，employee.id必须只有一个，如果员工有多个就业记录，结果必须得到最新的就业记录..

这就是我目前所拥有的。

SELECT * 
  FROM employmentrecords 
 WHERE employmentrecords.id IN(
    SELECT MAX(employmentrecords.id) 
      FROM employmentrecords 
     WHERE ((employmentrecords.date_end >='2017-08-22' 
        OR employmentrecords.date_end IS NULL 
        OR (employmentrecords.date_end <='2017-08-22' 
        AND employmentrecords.date_end >='2017-08-08')) 
        AND employmentrecords.date_hired <='2017-08-22') 
     GROUP 
        BY employmentrecords.employee_id) 
       AND employmentrecords.company_id<>0`

Hope any one would suggest a better approach.Thank you

Answer 1

我不确定我的问题是否清楚，如果有多个用户记录，下面的查询将为您提供最新的员工记录 -

destroy(req, res) {

    let id       = req.params.id;
    let language = {
        "code": req.body.code,
        "level": req.body.level
    };
    let type     = req.params.type;

    User.findOne({'_id': id}, function (err, user) {

        if (err) {
            return res.status(404).json({

                success: true,
                status: 404,
                data: err,
                message: "User does not exist",

            });
        }

        if (type === "teach") {

            for (let i = 0; i < user.languages.teach.length; i++)
                if (user.languages.teach[i].code === language.code) {
                    user.languages.teach[i].remove();
                    break;
                }

        }
        if (type === "learn") {
            //user.languages.learn.push(language);
        }

        console.log(user);

        user.save((err, user) => {

            return res.status(200).json({

                success: true,
                status: 201,
                data: user,
                message: "Successfully Deleted Language",

            });
        });

    });

}

JFYI，如果只有一个表从中获取数据，则不需要使用表名作为别名，这只会让你很难在去的时候读取查询。

Answer 2

SELECT id, max(date_hired)
      FROM employmentrecords 
     WHERE ((employmentrecords.date_end >='2017-08-22' 
        OR employmentrecords.date_end IS NULL 
        OR (employmentrecords.date_end <='2017-08-22' 
        AND employmentrecords.date_end >='2017-08-08')) 
        AND employmentrecords.date_hired <='2017-08-22') group by id

请为我简化SQL查询

2 个答案: