code: func (d MySQLDialect) ToSqlType(col *ColumnMap) string {
  	switch col.gotype.Kind() {
  	case reflect.Bool:
  		return "boolean"
  	case reflect.Int, reflect.Int16, reflect.Int32, reflect.Uint16, reflect.Uint32:
  		return "int"
  	case reflect.Int64, reflect.Uint64:
  		return "bigint"
  	case reflect.Float64, reflect.Float32:
  		return "double"
  	case reflect.Slice:
  		if col.gotype.Elem().Kind() == reflect.Uint8 {
  			return "mediumblob"
  		}
  	}
  
  	switch col.gotype.Name() {
  	case "NullableInt64":
  		return "bigint"
  	case "NullableFloat64":
  		return "double"
  	case "NullableBool":
  		return "tinyint"
  	case "NullableBytes":
  		return "mediumblob"
  	case "Time", "NullTime":
  		return "datetime"
  	}
  
  	maxsize := col.MaxSize
  	if col.MaxSize < 1 {
  		maxsize = 255
  	}
  	return fmt.Sprintf("varchar(%d)", maxsize)
  }
docs: // ToSqlType maps go types to MySQL types.