我有一个执行几个 MySQL 查询的路由 - 最后一个查询是 SELECT，使用路由中执行的上一个查询中的“电子邮件”值作为条件。我使用 MySQL Workbench 测试了其中一些“电子邮件”值并得到了结果，所以我很确定我的 JS 代码是错误的。不确定这是否需要采用 async/await 方法，但感觉可能是这样 - 我只是不确定从哪里开始。

这是错误：

以及引发错误（330）的行：

这是路线的完整代码：

// ROUND III: GETTING EVENTS AND ENROLLMENTS BY EMAIL FROM eLearningRecords TABLE; Then will need to create a SELECT query joining enrollmentrefresh and tb_elr_prereqs on emial. 
// All learndot enrollments GET route .......................................................................................................
// .................................................................................................................................
router.get("/elearning_enrollments", (err, res) => {
    // STEP 3 - DELETE EXISTING DATA FROM THE tb_elr_prereqs table ===========================================================
    // create the DELETE query and set to variable
    var sql_delete_events_and_enrollments = `DELETE FROM tb_elr_prereqs;`

    // execute the DELETE query
    pool2.query(sql_delete_events_and_enrollments, (err, results, fields) => {
        if (err) {
            console.log("Failed to delete records from tb_elr_prereqs!!!")
            console.log(err)
            res.sendStatus(500)
            return
        }
        console.log("Deleted the existing data from the tb_elr_prereqs table");
        // res.end()
    
    // END (STEP 3) DELETE QUERY SECTION ===========================================================================================

    // =============================================================================================================================

    // STEP 4 - GET EVENTS AND ENROLLMENTS FROM contact, enrollment, and location tables ===========================================

    // create a function
    function get_elearningrecords(){
    var sql_getemails = `SELECT email FROM enrollmentrefresh;`
    
    // execute the query
    pool.query(sql_getemails, (err, rows, results)=>{
        console.log("getting the emails from enrollmentrefresh table")
        console.log("sql_getemails" + Object.keys(rows).length)
        for(i=1;i <= Object.keys(rows).length; i++){
            if(rows[i] != undefined){
                for(var i in rows){
                    var email = JSON.stringify(rows[i].email)
                    var email = email.replace('"\\"', '')
                    var email = email.replace('\\""', '')
                    console.log(email)
                    var sql_getelr = 
                        `SELECT
                            registrationID,
                            courseName,
                            email
                        FROM
                            eLearningRecords
                        WHERE
                            email = "${email}"
                        (
                            SCORMLESSONSTATUS LIKE 'passed'
                            OR 
                            registrationstatus LIKE 'PASSED'
                        )
                        AND
                        (
                            (courseName LIKE '%Fundamentals%' AND courseName LIKE '%Part 3%')
                            OR 
                            courseName LIKE '%Creating Dashboards%'
                            OR 
                            courseName LIKE '%Advanced Searching%'
                            OR 
                            courseName LIKE '%Core Consultant Labs%'
                        );`

                    console.log(sql_getelr);
                    // execute the SELECT query
                    pool2.query(sql_getelr, (err, rows, results)=>{
                        console.log("sql_getelr" + Object.keys(rows).length)
                    })
                }
            }
        }
    })
}

    get_elearningrecords();

    })
})