如何解决将 mysql 查询行存储在变量中以供以后在另一个 mysql 查询中使用
我有 2 个不同的表,其中第一个表用于检索要存储在第二个表中的数据,例如,如果第一个表中有 3 个项目,我将运行 for 循环 3 次以检索信息并将其逐行存储在第二个表中,我还必须为第二个表的主键使用唯一 ID,因此我必须运行另一个 MysqL 查询以检索第二个表中的所有 ID 并将 1 添加到id 生成新 ID,但对我来说问题是当我尝试将 connection.query 放入另一个 connection.query 时,外部 connection.query 在运行内部 connection.query 之前运行 3 次,因此项目不会被存储并且 id 没有更新,给我一个重复的主键错误,我尝试使用函数但它没有帮助,这里是
app.get('/submit-check',function (request,response) {
function insert(sql2) {
connection.query(sql2,function (err,result1) {
if (err) throw err;
});
}
function other(value,index) {
let sql = "SELECT * FROM ORDERS"
connection.query(sql,results) {
var id;
if (results.length == 0) {
id = 0
} else {
id = results[results.length - 1].orderID;
}
// for (let j = 0; j < results.length; j++) {
// list.push(results[j].orderID)
// }
// if (list.length == 0) {
// id = 0
// }
// else {
// var largest = 0;
// for (let i = 0; i <= list.length; i++) {
// if (parseInt(list[i]) > largest) {
// var largest = parseInt(list[i]);
// }
// }
// id = largest + 1
// }
id = id + 1;
var add = request.query.state + " " + request.query.address + " " + request.query.Unumber + " " + request.query.zip
var custID = value[index].custID
var bookID = value[index].bookID
var Email = request.query.email
var CardName = request.query.cardname
var CardNumber = request.query.cardnumber
var ExDate = request.query.expmonth + "/" + request.query.expyear
var CVV = request.query.cvv
var qty = 1
var sql2 = "INSERT INTO orders (orderID,custID,bookID,QTY,CardName,CardNumber,ExDate,CVV,Email,Address,createdAt,updatedAt) VALUES('" + id + "','" + custID + "','" + bookID + "','" + qty + "','" + CardName + "','" + CardNumber + "','" + ExDate + "','" + CVV + "','" + Email + "','" + add + "',CURDATE(),CURDATE() )"
insert(sql2)
})
}
function setValue(value) {
for (let index = 0; index < value.length; index++) {
other(value,index)
}
}
let sql3 = "SELECT * FROM carts"
var cart_db;
connection.query(sql3,result) {
cart_db = result
setValue(cart_db)
})
// console.log(cart_db)
response.render("aftercheck",{ attributes: request.query,cardno: "****-****-****" + request.query.cardnumber.slice(-5,) });
})
先谢谢你
解决方法
您的代码有很多很多问题。我在这个基于等待/异步的重写中添加了 TODO 注释,您可能需要在其中修复一些问题。由于没有您的数据库,我自然无法对此进行测试。
async function queryP(connection,sql,parameters = undefined) {
return new Promise((resolve,reject) => {
connection.query(sql,parameters,function (err,results) {
if (err) return reject(err);
resolve(results);
});
});
}
app.get("/submit-check",async function (request,response) {
// TODO: these need to be validated
const {
address,Unumber,zip,expyear,state,expmonth,email: Email,cardname: CardName,cardnumber: CardNumber,cvv: CVV,} = request.query;
const add = `${state} ${address} ${Unumber} ${zip}`;
const ExDate = `${expmonth}/${expyear}`;
const cartData = await queryP(connection,"SELECT * FROM carts"); // TODO: this is not safe with multiple customers
const [maxOrderIdRow] = await queryP(connection,"SELECT MAX(id) as maxid FROM orders");
const orderId = (maxOrderIdRow.maxid || 0) + 1; // TODO: this is not safe in the face of concurrent requests
// Using a for loop rather than .map and await and so on is simpler here
for (let i = 0; i < cartData.length; i++) {
const cartRow = cartData[i];
const custID = cartRow.custID;
const bookID = cartRow.bookID;
const qty = 1;
// TODO: rethink how credit cards are saved – we can't save them in the database like this or we'll be out of business
await queryP(
connection,`INSERT INTO orders (orderID,custID,bookID,QTY,CardName,CardNumber,ExDate,CVV,Email,Address,createdAt,updatedAt) VALUES(?,?,CURDATE(),CURDATE() )`,[orderId,qty,add],);
}
response.render("aftercheck",{
attributes: request.query,cardno: "****-****-****" + CardNumber.slice(-5),});
});
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