docs: function _transformToSafeValue(input, column){
    var out = input;
    var datatype = column.sql_type;
    var nullable = column.nullable;
    if( input === '' ){
      //empty string.
      if(datatype==='datetime'|| datatype==='timestamp' ||_.startsWith(datatype, 'int') || _.startsWith(datatype, 'num') || _.startsWith(datatype, 'dec')){
        if(nullable){
          out = null;
        } else {
          throw new Error(column.column + ' is not permitted to be empty.')
        }
      }
  
    } else if( !_.isNil(input) ) {
      //not null, not undefined
      if(datatype==='datetime'|| datatype==='timestamp'){
        out = moment(input).format('YYYY-MM-DD HH:mm:ss');
      }
    }
    return out;
  }