### Go与字段类型对应表
如果不使用tag来定义field对应的数据库字段类型，那么系统会自动给出一个默认的字段类型，对应表如下：
| go type's kind | value method | xorm type |
|-----|-----|-----|
| implemented Conversion | Conversion.ToDB / Conversion.FromDB | Text |
| int, int8, int16, int32, uint, uint8, uint16, uint32 | | Int |
| int64, uint64 | | BigInt |
| float32 | | Float |
| float64 | | Double |
| complex64, complex128 | json.Marshal / json.UnMarshal | Varchar(64) |
| []uint8 | | Blob |
| array, slice, map except []uint8 | json.Marshal / json.UnMarshal | Text |
| bool | 1 or 0 | Bool |
| string | | Varchar(255) |
| time.Time | | DateTime |
| cascade struct | primary key field value | BigInt |
| struct | json.Marshal / json.UnMarshal | Text |
| Others | | Text |
