Question

当我使用此代码时，它只更新第一个值的数据库的一个值。它不适用于循环;只有一行受到影响。我想更新所有行。如何从表中选择列值并将其更新为循环中的其他列值？

asyncloop方法： -

   function readData () {
      return new Promise (function(resolve,rejection){
        conn.connect().then(function () {
          var request = new sql.Request(conn);
          request.query('Select * FROM demo Order by id  ;', function (err, data) {
            if (err) { console.log(err) }
            else {
              try {
               resolve(data)
                conn.close();
              }
              catch (err) {
                console.log(err);
              }
              }
          });
        });
      });
    }

   function writedata() {
  return new Promise(function (resolve, rejection) {
    let count = 0
    asyncLoop(temp, function (item, next){
      asyncLoop(id,function(newitem,newnext){
      conn.close();
      conn.connect().then(function () {
        var request = new sql.Request(conn);
        console.log(item);
        console.log(newitem);
        request.input("language", sql.VarChar, item)
        request.input("id", sql.SmallInt, newitem)
        request.query('update demo set ru = @language where  id = @id ;', function (err, data) {
          if (err) {
            console.log(err)
          } else {
            try {
              count++
              conn.close();
              if (count == 4) {
                resolve(data)
              }
            } catch (err) {
              console.log(err);
            }
            next();
            newnext();
          }
        });
      });
    });
    });
  });
}



readData().then(function (data) {
  for (var i = 1; i < 5; i++) {
    temp.push(data['recordset'][i]['EN']);
    id.push(data['recordset'][i]['ID']);
  }
  writedata().then(function (data) {
    console.log(data);
  });
});

使用asyncloop更新了代码，但有一些循环问题

Answer 1

尝试下面的代码，通知我任何错误。另外，根据需要修改计数值：

    function writedata() {
        return new Promise(function (resolve, rejection) {
            let count = 0
            for (i = 0; i < 5; i++) {
                conn.close();
                conn.connect().then(function () {
                    var request = new sql.Request(conn);
                    console.log(temp[i]);
                    console.log(id[i]);

                    request.input("language", sql.VarChar, temp[i])
                    request.input("id", sql.SmallInt, id[i])
                    request.query('update demo set ru = @language where  id = @id ;', function (err, data) {
                        if (err) {
                            console.log(err)
                        } else {
                            try {
                                count++
                                conn.close();
                                if(count == 5)
                                   resolve()

                            } catch (err) {
                                console.log(err);
                            }
                        }
                    });
                });

            }

        });
    }

Answer 2

请尝试Asyncloop，而不是for循环下面是相同的语法。

asyncLoop(ARRAY, function(item, next) {

    [Function/Operation block]
        next();
    }
});

}, function(error) {
    [Error Handling Block]
});

Answer 3

尝试下面的代码，我希望它有所帮助

    // If this.notification has the multiple subscriptions 
    if(this.notifications && this.notifications.length >0)
    {
        this.notifications.forEach((s) => {
            if(!s.closed)    
                s.unsubscribe();
        });        
    }
    // if this.subscription has direct object
    if(this.subscription && !this.subscription.closed)
        this.subscription.unsubscribe();
}

NodeJS数据库更新查询？

3 个答案: