我将使用不同的 Id 值来获取我的数据库两次。但我需要将这两个查询保存在某处,然后将它们发送到 res.render。我已经尝试保存在数组中,但它返回未定义。
app.post('/searchInventory', urlencodedParser, function(req, res){
con.query("SELECT id FROM products WHERE name LIKE '%" + req.body.keyword + "%'", function(err, result){
data = [];
for(var a = 0; a < result.length; a++){
console.log(a);
con.query("SELECT products.id AS id, products.name AS name, products.price AS price, SUM(enter.quantity) AS quantity FROM products JOIN enter ON products.id = enter.id_prod WHERE enter.id_prod = "+mysql.escape(result[a].id)+";", function(err, results, fields){
// I need to store the query from here
data =+ results
});
}
console.log(data); //Undefined
res.render('inventory', {results: results});
});
})
最佳答案
问题是关于需要注意的异步数据库查询。 首先,您可以做的是创建一个查询 promise ,让它变得简单易读。
function dbQueryPromise(query) {
return new Promise((resolve, reject) => {
con.query(query, (err, results) => {
if(err) return reject(err);
resolve(results);
})
})
}
现在您可以使用这个 promise 来处理您需要的行为:
dbQueryPromise("SELECT id FROM products WHERE name LIKE '%" + req.body.keyword + "%'")
.then(results => {
const promiseArray = results.map(result => {
return dbQueryPromise("SELECT products.id AS id, products.name AS name, products.price AS price, SUM(enter.quantity) AS quantity FROM products JOIN enter ON products.id = enter.id_prod WHERE enter.id_prod = "+mysql.escape(result.id)+";")
})
Promise.all(promiseArray).then(allResults => { res.render('inventory', { results: allResults})})
})
关于javascript - store如何查询Mysql,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/54994566/