Question

I want to return a JSON object from a database (MyTable) which contains two columns – ID (int) and Name (string).

The script below produces a JSON like:

[{"ID":"0","Name":"John"},{"ID":"1","Name":"Doe"}]

You can see, that the ID is returned as a string. How can I accomplish it in a way that an ID would be returned as integer:

[{"ID":0,"Name":"John"},{"ID":1,"Name":"Doe"}]

I do not want to read and parse the result array from the ODBC since I want to use generic queries like:

SELECT * FROM TableXXX

Here is my script:

    //connection
    $connstr = "Driver={SQL Server Native Client 10.0};Server=" . $this->server . ";Database=" . $this->database . ";"; 
    $conn=odbc_connect($connstr, $this->user, $this->password);
    if (!$conn) {exit("Connection Failed: " . $conn);}

    //execute sql
    $rs=odbc_exec($conn,"SELECT ID, Name FROM MyTable");
    if (!$rs) {exit("Error in SQL");}
    //retreive data into array
    $data = array();
    $i=0;
    while( $row = odbc_fetch_array($rs) ) {
        $data[$i] = $row;
        $i++;
    } 
    odbc_close($conn);
    //output as json string
    echo json_encode($data);

Answer 1

In general, there are no common data types in ODBC. It would be dependent on the individual ODBC drivers (and possibly different from every vendor if it were supported). I have not seen anything in the ODBC specification that describes “common” data type names. Most calls into ODBC do go through the ODBC driver manager, but I am not aware of any situations in which it would perform translation/modification of SQL statements being passed through it.

It means, that ODBC driver would not return data types. If you want to return a JSON object conatining else than strings you would have to map the data individually column by column. You can retrieve data types of the field by odbc_field_type function.

However you have to know that each database vendor returns different field names (e.g. varchar, nvarchar, ….).

Then use something like (just in reverse order):

$type_map = array(
'varchar' => 'string',
'char' => 'string',
'text' => 'string',
);

$column_type = 'text'; // get from DB query
$my_var = 'some string';
$var_type = gettype($my_var);

if(array_key_exists($column_type, $type_map) and
   $type_map[$column_type] == $var_type) {
   //proceed with insert of record
}

Hope it helps.