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[[database drivers.htm|Database Drivers]]

[[choosing the right database driver.htm|Choosing the Right Database Driver]]

[[common database driver features.htm|Common Database Driver Features]]

[[driver strings.htm|Driver Strings]]

[[dbaseiv database driver.htm#bpqx8r|dBaseIV:Specifications]]

[[dbaseiv database driver.htm#a6b012s|dBaseIV:Data Types]]

[[dbaseiv supported commands and attributes.htm|dBaseIV:Supported Commands and Attributes]]

[[dbaseiv driver strings.htm|dBaseIV:Driver Strings]]

[[dbaseiv other.htm|dBaseIV:Other]]

**dBaseIV:Specifications**

The dBase4 file driver is compatible with dBase IV. The default data file extension is *.DBF.

Keys and Indexes exist as separate files from the data file. Keys are dynamic--they automatically update as the data file changes. Indexes are static--they do not automatically update, but instead require the BUILD statement for updating. The default file extension for the index file is *.NDX.

dBase IV supports multiple index files, whose extension is *.MDX. The miscellaneous section describes procedures for using .MDX files.

The driver stores records as fixed length. It stores memo fields in a separate file. The memo file name takes the first eight characters of the File Label plus an extension of .DBT.

| **Files:** | **ClaDB4L.LIB** | Windows Static Link Library |
|  | **ClaDB4.LIB** | Windows Export Library |
|  | **ClaDB4.DLL** | Windows Dynamic Link Library |

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**dBase IV was never as widely adopted as dBase III. Choose this driver only when you must share data with an end-user using dBase IV.**

**dBaseIV:Data Types**

The xBase file format stores all data as ASCII strings. You may either specify STRING types with declared pictures for each field, or specify native Clarion types, which the driver converts automatically.

| __**dBase data type**__ | __**Clarion data type**__ | __**STRING w/ picture**__ |
| **Date** | **DATE** | **STRING(@D12)** |
| ***Numeric** | **REAL** | **STRING(@N-_p.d)** |
| ***Logical** | **BYTE** | **STRING(1)** |
| **Character** | **STRING** | **STRING** |
| ***Memo** | **MEMO** | **MEMO** |

If your application reads and writes to existing files, a pictured STRING will suffice. However, if your application //creates //a dBase IV file, you may require additional information for these dBase IV types:

*****      To create a Numeric field in the Data Dictionary, choose the REAL data type. In the External Name field on the Attributes tab, specify '//NumericFieldName//=N(//Precision//,//DecimalPlaces//)' where //NumericFieldName// is the name of the field, //Precision// is the precision of the field and //DecimalPlaces// is the number of decimal places. With a REAL data type, you cannot access the Character or Places fields in the Field definition, you must specify those attributes with an expression in the External Name Field on the Attributes tab.

For example, if you want to create a field called Number with nine significant digits and two decimal places, enter 'Number=N(9,2) in the External Name field on the Attributes tab of the Field properties in the Data Dictionary.

If you're hand coding a native Clarion data type, add the NAME attribute using the same syntax.

If you're hand coding a STRING with picture, STRING(@N-_9.2), NAME('//Number//'), where //Number //is the field name.

*****      To create a Logical field, using the data dictionary, choose the BYTE data type. There are no special steps; however, see the miscellaneous section for tips on reading the data from the field.

If you're hand coding a STRING with picture, add the NAME attribute: STRING(1), NAME('//LogFld// = L')**.**

*****      To create a Date field, using the data dictionary, choose the DATE data type, rather than LONG, which you usually use for the TopSpeed or Clarion file formats.

*****      MEMO field declarations require the a pointer field in the file's record structure. Declare the pointer field as a STRING(10) or a LONG. This field will be stored in the .DBF file containing the offset of the memo in the .DBT file. The MEMO declaration must have a NAME() attribute naming the pointer field. An example file declaration follows:

**File FILE, DRIVER('dBase4')**

**Memo1 MEMO(200),NAME('Notes')**

**Memo2 MEMO(200),NAME('Text')**

**Rec   RECORD**

**Mem1Ptr LONG,NAME('Notes')**

**Mem2Ptr STRING(10),NAME('Text')**

**      END**

**     END**

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**Use the File Import Utility in the Clarion Dictionary Editor to define your files.**

**dBaseIV:File Specifications/Maximums**

**File Size:             2,000,000,000 bytes**

**Records per File:      1,000,000,000**

**Record Size:           4,000 bytes**

**Field Size**

**  Character:           254 bytes**

**  Date:                8 bytes**

**  Logical:             1 byte**

**  Numeric:             20 bytes including decimal point**

**  Float:               20 bytes including decimal point**

**  Memo:                64K (see note)**

**Fields per Record:     512**

**Field Name:            12 characters**

**Keys/Indexes per File: **

**      .NDX:            No Limit**

**      .MDX             47 tags per .MDX files**

**Key Sizes**

**  Character:           100 bytes**

**  Numeric, Date:       8 bytes**

**Memo fields per File:  Dependent on available memory**

**Open Files:            Operating system dependent**