我正在尝试使用 mysql javascript API 删除数据库中的一条记录

Question

我正在尝试使用 javascript mysql API 从数据库中删除一条记录。 我创建了一个表，其中列出了数据库中的记录。 我添加了一个删除按钮和一个查看详细信息按钮。 现在，当我单击删除按钮时。 删除按钮会删除最后一行，而不是我单击的按钮所在的行。 我的查看详细信息按钮工作正常，直到现在它也在做同样的事情。 它查看最后一行的信息，而不是包含查看按钮的行。 当我添加删除按钮代码时，这开始发生。 代码如下。 请帮助我了解发生了什么。

HTML代码。 我已经编辑并添加了 html 代码。 下面是典型的一行。

<tr class="record" id="record153">
<td>John Doe</td>
<td>11p</td>
<td>10</td>
<td>Cotton</td>
<td><p>Compound D: ranging from 464.29kg to  535.71kg.<br>  Ammonium nitrate: ranging from 223.88kg to 253.73kg.<br> Potasium nitrate: ranging from 0.00kg to 0.00kg.</p></td>
<td><button>View Detail</button><button>Delete</button></td>
</tr>

Javascript代码

var historicalContent = document.querySelector('.historical-data');
    window.views.peek().style.display = "none";
    historicalContent.style.display = 'block';
    var backButton = document.querySelector('#back');
    backButton.style.display = 'block';
    var dashboard = document.querySelector("#dashboard");
    window.views.push(dashboard);
    window.views.push(historicalContent);

    var table = document.querySelector('.table-container table');
    let sql = `SELECT * FROM lab_results`;
    let labResultsCollection;
    //fire
    connection.query(sql, function (err, results, fields) {
        if (err) throw err;
        else {
            labResultsCollection = results;
            console.log(results);
            for (result of results) {
                let record = document.createElement('tr');
                record.className = 'record';
                record.id = 'record' + result.id;
                let farmerName = document.createElement('td');
                farmerName.innerText = result.name;
                let reference = document.createElement('td');
                reference.innerText = result.ref;
                let labNumber = document.createElement('td');
                labNumber.innerText = result.lab_number;
                let recommendations = document.createElement('td');
                let cropName = document.createElement('td');

                connection.query(`SELECT crop_id FROM crop_has_lab_results WHERE lab_results_id = ${result.id}`,
                    function (err, bresult, fields) {
                        if (err) {
                            throw err
                        } else {
                            //now get the id of the crop
                            crop_id = bresult[0].crop_id;
                            //fire
                            connection.query(`SELECT name FROM crop WHERE id = ${crop_id}`,
                                function (err, cresult, fields) {
                                    if (err) throw err;
                                    else {

                                        cropName.innerText = cresult[0].name;

                                    }
                                })
                        }
                    })

                connection.query(`SELECT recommendation_id FROM lab_results_has_recommendation WHERE lab_results_id = ${result.id}`,
                    function (err, bresult, fields) {
                        if (err) {
                            throw err
                        } else {
                            //now get the id of the crop
                            if (bresult.length > 0) {
                                console.log(bresult);
                                recommendation_id = bresult[0].recommendation_id;
                                //fire
                                connection.query(`SELECT text1,text2,text3 FROM recommendation WHERE id = ${recommendation_id}`,
                                    function (err, cresult, fields) {
                                        if (err) throw err;
                                        else {

                                            let str = `<p>${cresult[0].text1}.<br/> ${cresult[0].text2}.<br/> ${cresult[0].text3}.</p>`;
                                            recommendations.innerHTML = str;

                                        }
                                    })
                            }
                        }
                    })
                record.appendChild(farmerName);
                record.appendChild(reference);
                record.appendChild(labNumber);
                record.appendChild(cropName);
                record.appendChild(recommendations);
                let actions = document.createElement('td')
                let viewDetail = document.createElement('button');
                viewDetail.innerText = 'View Detail';
                let deleteRecord = document.createElement('button');
                deleteRecord.innerText = 'Delete';
                actions.appendChild(viewDetail);
                actions.appendChild(deleteRecord);
                record.appendChild(actions);



                deleteRecord.addEventListener('click', function () {
                    let xmysql = `DELETE FROM lab_results_has_recommendation WHERE lab_results_id = ${result.id}`;
                    let xmysql2 = `DELETE FROM crop_has_lab_results WHERE lab_results_id = ${result.id}`;
                    let xmysql3 = `DELETE FROM lab_results WHERE id = ${result.id}`;
                    console.log(xmysql, xmysql2, xmysql3);
                    connection.query(xmysql, function (err, bresult, fields) {
                        if (err) throw err;
                        else {
                            connection.query(xmysql2, function (err, cresult, fields) {
                                if (err) throw err;
                                else {
                                    connection.query(xmysql3, function (err, dresult, fields) {
                                        if (err) throw err;
                                        else {
                                            let record = document.getElementById(`record${result.id}`);
                                            console.log("Id of the removed", result.id);
                                            record.remove();
                                        }
                                    })
                                }
                            })

                        }
                    })
                })


                viewDetail.addEventListener('click', function () {
                    var detailPanel = document.querySelector('#detail-pane');
                    window.views.peek().style.display = 'none';
                    detailPanel.style.display = 'block';
                    detailPanel.innerHTML = '';
                    window.views.push(detailPanel);
                    let id = result.id;
                    let mysql = `SELECT * FROM lab_results WHERE id = ${id}`

                    connection.query(mysql, function (err, mresult, fields) {
                        if (err) {
                            throw err;
                        } else {
                            let myresult = mresult[0];
                            var name = document.createElement('h3');
                            name.innerText = myresult.name;
                            detailPanel.appendChild(name);
                            var lab_number = document.createElement('p');
                            lab_number.innerText = `Lab number: ${myresult.lab_number}`;
                            detailPanel.appendChild(lab_number);
                            var ref = document.createElement('p')
                            ref.innerText = `Reference: ${myresult.ref}`;
                            detailPanel.appendChild(ref);
                            var color = document.createElement('p');
                            color.innerText = `Color: ${myresult.color}`;
                            detailPanel.appendChild(color);
                            var texture = document.createElement('p');
                            texture.innerText = `Texture: ${myresult.texture}`;
                            detailPanel.appendChild(texture);
                            var pH = document.createElement('p');
                            pH.innerText = `pH: ${myresult.pH}`;
                            detailPanel.appendChild(pH);
                            var free_carbonate = document.createElement('p');
                            free_carbonate.innerText = `Free carbonate: ${myresult.free_carbonate}`;
                            detailPanel.appendChild(free_carbonate);
                            var conductivity = document.createElement('p');
                            conductivity.innerText = `Conductivity: ${myresult.conductivity}`;
                            detailPanel.appendChild(conductivity);
                            var nitrogen = document.createElement('p');
                            nitrogen.innerText = `Initial nitrogen ${myresult.nitrogen}`;
                            detailPanel.appendChild(nitrogen);
                            var nitrogen_after = document.createElement('p');
                            nitrogen_after.innerText = `Nitrogen after incubation ${myresult.m_nitrogen_init}`;
                            detailPanel.appendChild(nitrogen_after);
                            var phosphorus = document.createElement('p');
                            phosphorus.innerText = `Phosphorus: ${myresult.phosphorus}`;
                            detailPanel.appendChild(phosphorus);
                            var potasium = document.createElement('p');
                            potasium.innerText = `Potasium: ${myresult.potasium}`;
                            detailPanel.appendChild(potasium);
                            var calcium = document.createElement('p');
                            calcium.innerText = `Calcium: ${myresult.calcium}`;
                            detailPanel.appendChild(calcium);
                            var magnesium = document.createElement('p');
                            magnesium.innerText = `Magnesium: ${myresult.magnesium}`;
                            detailPanel.appendChild(magnesium);
                            var total_bases = document.createElement('p');
                            total_bases.innerText = `Total bases: ${myresult.total_bases}`;
                            detailPanel.appendChild(total_bases);

                            let mysql2 = `SELECT * FROM lab_results_has_recommendation WHERE lab_results_id = 
                                    ${myresult.id}`;
                            connection.query(mysql2, function (erra, mresult2, fields) {
                                if (err) throw err;
                                else {
                                    let myresult2 = mresult2[0];
                                    let mysql3 = `SELECT * FROM recommendation WHERE id = ${myresult2.recommendation_id}`;
                                    connection.query(mysql3, function (err, mresult3, fields) {
                                        if (err) throw err;
                                        else {
                                            let myresult3 = mresult3[0];
                                            let divider = document.createElement('hr');
                                            divider.width = '100%';
                                            detailPanel.appendChild(divider);
                                            let recommendationView = document.createElement('div');
                                            let recommendationHeading = document.createElement('h4');
                                            recommendationHeading.innerText = 'Recommendation';
                                            recommendationView.appendChild(recommendationHeading);

                                            var nitrogen2 = document.createElement('p');
                                            nitrogen2.innerText = `Nitrogen: from ${myresult3.nitrogen} `;
                                            recommendationView.appendChild(nitrogen2);
                                            var phosphorus2 = document.createElement('p');
                                            phosphorus2.innerText = `Phosphorus: from ${myresult3.phosphorus}`;
                                            recommendationView.appendChild(phosphorus2);
                                            var potasium2 = document.createElement('p');
                                            potasium2.innerText = `Potasium: from ${myresult3.potasium}`;
                                            recommendationView.appendChild(potasium2);
                                            var lime = document.createElement('p');
                                            lime.innerText = `Lime: from ${myresult3.lime}`;
                                            recommendationView.appendChild(lime);
                                            var text1 = document.createElement('p');
                                            var text2 = document.createElement('p');
                                            var text3 = document.createElement('p');
                                            text1.innerText = myresult3.text1;
                                            text2.innerText = myresult3.text2;
                                            text3.innerText = myresult3.text3;
                                            recommendationView.appendChild(text1);
                                            recommendationView.appendChild(text2);
                                            recommendationView.appendChild(text3);
                                            detailPanel.appendChild(recommendationView);


                                        }
                                    })
                                }
                            })

                        }
                })


            })
            table.appendChild(record);

Answer 1

在for (result of results) {您不使用let或const声明result ，这意味着它将使变量隐式全局化。

你应该写for (const result of results) { ( let在技​​术上可行，但它更清楚地表明该范围的结果在任何时间点都没有改变。

Answer 2

问题是您没有在删除侦听器中传递结果 ID。 它是从作用域中选取的，作用域是 for 循环的最后一行。 因此，您的问题是预期行为。

您应该阅读JS Closures以了解更多信息。