Strings are converted to the data type of buffer

Hello! I have the following table:

CREATE TABLE GROUP_ORDER (
    ID                 INTEGER NOT NULL,
    SOURCE_ID          INTEGER NOT NULL,
    NUMBER             VARCHAR(200) NOT NULL,
    IS_OPTIMIZED       INTEGER NOT NULL,
    "DATE"             TIMESTAMP NOT NULL,
    NUMBER_ORDER_LIST  VARCHAR(5000)
);

I make this request:

select * from GROUP_ORDER

And I get this answer:

[ { ID: 2,
    SOURCE_ID: 5,
    NUMBER: <Buffer 31>,
    IS_OPTIMIZED: 0,
    DATE: 2017-01-16T22:00:00.000Z,
    NUMBER_ORDER_LIST: <Buffer 30 32 36 33 31 5f 30 32 36 31 34> },
  { ID: 534,
    SOURCE_ID: 3,
    NUMBER: <Buffer 33>,
    IS_OPTIMIZED: 1,
    DATE: 2016-04-19T22:00:00.000Z,
    NUMBER_ORDER_LIST: <Buffer 31 36> },
  { ID: 539,
    SOURCE_ID: 9,
    NUMBER: <Buffer 42 49 47 5f 31>,
    IS_OPTIMIZED: 1,
    DATE: 2016-05-21T22:00:00.000Z,
    NUMBER_ORDER_LIST: <Buffer 31 2c 20 32 2c 20 33> },
  { ID: 540,
    SOURCE_ID: 10,
    NUMBER: <Buffer 42 49 47 5f 32>,
    IS_OPTIMIZED: 1,
    DATE: 2016-05-21T22:00:00.000Z,
    NUMBER_ORDER_LIST: <Buffer 31 32 33 2c 20 35 2c 20 36> } ]

Why, instead Strings Variables I have variables of type Buffer (see fields NUMBER and NUMBER_ORDER_LIST)?

On database this one in the form of a buffer to another as a string.

[e-baron]

Hello, I have used this solution in order to decode buffer objects:

1. Find out what is the default character set of your DB. I did not know, so I tested those listed here https://nodejs.org/api/buffer.html (utf8, latin1…)
2. Use function toString( ‘your character set’) on the buffer objects.

Here is an example of code illustrating how to print to the console the string encoded in the buffer:

db.query('SELECT FIRST 10 NOM,PRENOM FROM ETUD', function(err, result) {
            if (result != undefined)
                { 
                for (i=0; i< result.length ; i++){
                    /* string / text in firebird are converted to buffer objects by NodeJS. Those buffer are encoded in latin1, apparently the default character set of our DB */  
                    console.log("Student: " , result[i].NOM.toString('latin1'), " ", result[i].PRENOM.toString('latin1'));
                }                

                }
            else
                console.log("No results");
            db.detach();
        });

[cesarbalbinott]

use: select ID, SOURCE_ID, cast(NUMBER as varchar(50) character set utf8) "NUMBER", IS_OPTIMIZED, DATE, cast(NUMBER_ORDER_LIST as varchar(50) character set utf8) "NUMBER_ORDER_LIST" from GROUP_ORDER