DBCREATE() Create a database file from a database structure array ------------------------------------------------------------------------------ Syntax DBCREATE(<cDatabase>, <aStruct> [<cDriver>]) --> NIL Arguments <cDatabase> is the name of the new database file, with an optional drive and directory, specified as a character string. If specified without an extension, .dbf is assumed. <aStruct> is an array that contains the structure of <cDatabase> as a series of subarrays, one per field. Each subarray contains the definition of each field's attributes and has the following structure: Field Definition Subarray ------------------------------------------------------------------------ Position Metasymbol Dbstruct.ch ------------------------------------------------------------------------ 1 cName DBS_NAME 2 cType DBS_TYPE 3 nLength DBS_LEN 4 nDecimals DBS_DEC ------------------------------------------------------------------------ <cDriver> specifies the replaceable database driver (RDD) to use to process the current work area. <cDriver> is the name of the RDD specified as a character expression. If you specify <cDriver> as a literal value, you must enclose it in quotes. Returns DBCREATE() always returns NIL. Description DBCREATE() is a database function that creates a database file from an array containing the structure of the file. You may create the array programmatically or by using DBSTRUCT(). DBCREATE() is similar to the CREATE FROM command which creates a new database file structure from a structure extended file. Use CREATE or COPY STRUCTURE EXTENDED commands to create a structure extended file. Before using DBCREATE(), you must first create the <aStruct> array and fill it with the field definition arrays according to the structure in Field Definition Subarray table (above). There are some specific rules for creating a field definition array, including: . Specify all field attributes with a value of the proper data type for the attribute. The decimals attribute must be specified-- even for non-numeric fields. If the field does not have a decimals attribute, specify zero. . Specify the type attribute using the first letter of the data type as a minimum. Use longer and more descriptive terms for readability. For example, both "C" and "Character" can be specified as the type attribute for character fields. . In Clipper, character fields contain up to 64,000 characters. Unlike the CREATE FROM command, DBCREATE() does not use the decimals attribute to specify the high-order part of the field length. Specify the field length directly, regardless of its magnitude. To make references to the various elements of the field definition subarray more readable, the header file called Dbstruct.ch is supplied. It contains the #defines to assign a name to the array position for each field attribute. It is located in \CLIP53\INCLUDE. Notes . Duplicate field names: DBCREATE() does not check for duplicate field names. Therefore, be careful not to use the same field name twice. . EG_ARG error: DBCREATE() generates an EG_ARG error if the filename is NIL. Examples . This example creates an empty array and then adds field definition subarrays using the AADD() function before creating People.dbf. You might use this technique to add field definitions to your structure array dynamically: aDbf := {} AADD(aDbf, { "Name", "C", 25, 0 }) AADD(aDbf, { "Address", "C", 1024, 0 }) AADD(aDbf, { "Phone", "N", 13, 0 }) // DBCREATE("People", aDbf) . This example performs the same types of actions but declares the structure array as a two-dimensional array, and then uses subscript addressing to specify the field definitions. It will be created using the DBFMDX RDD: #include "Dbstruct.ch" // LOCAL aDbf[1][4] aDbf[1][ DBS_NAME ] := "Name" aDbf[1][ DBS_TYPE ] := "Character" aDbf[1][ DBS_LEN ] := 25 aDbf[1][ DBS_DEC ] := 0 // DBCREATE("Name", aDbf, "DBFMDX") Files Library is CLIPPER.LIB, header file is Dbstruct.ch.
See Also: AFIELDS()* COPY STRU EXTE CREATE FROM DBSTRUCT()