DbfDataReader use old DBF specification #35
Description
Below some quotes from Microsoft Visual Foxpro documentation.
Very impotant byte for correct table encoding - 29 | Code page mark
Table Header Record Structure
Byte offset | Description
- 0 | File type:
0x02 FoxBASE / dBase
0x03 FoxBASE+ / FoxPro /dBase III PLUS / dBase IV, no memo
0x30 Visual FoxPro
0x31 Visual FoxPro, autoincrement enabled
0x32 Visual FoxPro, Varchar, Varbinary, or Blob-enabled
0x43 dBASE IV SQL table files, no memo
0x63 dBASE IV SQL system files, no memo
0x83 FoxBASE+/dBASE III PLUS, with memo 0x8B dBASE IV with memo
0xCB dBASE IV SQL table files, with memo
0xF5 FoxPro 2.x (or earlier) with memo
0xFB FoxBASE (?) - 1 - 3 | Last update (YYMMDD)
- 4 – 7 | Number of records in file
- 8 – 9 | Position of first data record
- 10 – 11 | Length of one data record, including delete flag
**- 12 – 27 | Reserved - 28 | Table flags:
0x01 file has a structural .cdx
0x02 file has a Memo field
0x04 file is a database (.dbc) This byte can contain the sum of any of the above values. For example, the value 0x03 indicates the table has a structural .cdx and a Memo field. - 29 | Code page mark
- 30 – 31 | Reserved, contains 0x00
- 32 – n | Field subrecords The number of fields determines the number of field subrecords. One field subrecord exists for each field in the table.
- n+1 | Header record terminator (0x0D)
- n+2 to n+264 | A 263-byte range that contains the backlink, which is the relative path of an associated database (.dbc) file, information. If the first byte is 0x00, the file is not associated with a database. Therefore, database files (.DBC) always contain 0x00.**
Field Subrecords Structure
| Byte offset | Description |
|---|---|
| 0 – 10 | Field name with a maximum of 10 characters. If less than 10, it is padded with null characters (0x00). |
| 11 | Field type: |
| W - Blob | |
| C – Character | |
| C – Character (binary) | |
| Y – Currency | |
| B – Double | |
| D – Date | |
| T – DateTime | |
| F – Float | |
| G – General | |
| I – Integer | |
| L – Logical | |
| M – Memo | |
| M – Memo (binary) | |
| N – Numeric | |
| P – Picture | |
| Q - Varbinary | |
| V - Varchar | |
| V - Varchar (binary) | |
| Note For each Varchar and Varbinary field, one bit, or "varlength" bit, is allocated in the last system field, which is a hidden field and stores the null status for all fields that can be null. If the Varchar or Varbinary field can be null, the null bit follows the "varlength" bit. If the "varlength" bit is set to 1, the length of the actual field value length is stored in the last byte of the field. Otherwise, if the bit is set to 0, length of the value is equal to the field size. | |
| 12 – 15 | Displacement of field in record |
| 16 | Length of field (in bytes) |
| 17 | Number of decimal places |
| 18 | Field flags: |
| 0x01 System Column (not visible to user) | |
| 0x02 Column can store null values | |
| 0x04 Binary column (for CHAR and MEMO only) 0x06 (0x02+0x04) When a field is NULL and binary (Integer, Currency, and Character/Memo fields) | |
| 0x0C Column is autoincrementing | |
| 19 - 22 | Value of autoincrement Next value |
| 23 | Value of autoincrement Step value |
| 24 – 31 | Reserved |