一個学生成績排名的實現程序，以及Custom定制類的用法示例
程序代码：
CLEAR ALL
SET TALK OFF
SET SAFETY OFF
CLOSE DATABASES ALL
CLEAR
PUBLIC gaSubjects[12]
gaSubjects[1] = CREATEOBJECT("myField", "化學成績", "S01", "N", 6, 2, .T., 0)
gaSubjects[2] = CREATEOBJECT("myField", "數學成績", "S02", "N", 6, 2, .T., 0)
gaSubjects[3] = CREATEOBJECT("myField", "物理成績", "S03", "N", 6, 2, .T., 0)
gaSubjects[4] = CREATEOBJECT("myField", "語文成績", "S04", "N", 6, 2, .T., 0)
gaSubjects[5] = CREATEOBJECT("myField", "英語成績", "S05", "N", 6, 2, .T., 0)
gaSubjects[6] = CREATEOBJECT("myField", "政治成績", "S06", "N", 6, 2, .T., 0)
gaSubjects[7] = CREATEOBJECT("myField", "化學名次", "R01", "I")
gaSubjects[8] = CREATEOBJECT("myField", "數學名次", "R02", "I")
gaSubjects[9] = CREATEOBJECT("myField", "物理名次", "R03", "I")
gaSubjects[10] = CREATEOBJECT("myField", "語文名次", "R04", "I")
gaSubjects[11] = CREATEOBJECT("myField", "英語名次", "R05", "I")
gaSubjects[12] = CREATEOBJECT("myField", "政治名次", "R06", "I")
Create_DataTable(@gaSubjects)
Do_Sort(@gaSubjects)
CLOSE DATABASES ALL
CLEAR ALL
RETURN
*---------------------------
* 創建數據表及測試數據
*---------------------------
PROCEDURE Create_DataTable(taSubjects)
LOCAL lcDataBase, lcTable
LOCAL lnIndex, lnRecord, lcField
lcDataBase = "Test"
lcTable = "Scores"
IF !FILE(lcDataBase + ".DBC")
CREATE DATABASE (lcDataBase)
ELSE
OPEN DATABASE (lcDataBase)
ENDIF
SET DATABASE TO (lcDataBase)
IF INDBC(lcTable, "TABLE")
DROP TABLE (lcTable)
ENDIF
CREATE TABLE &lcTable (ID C(10) PRIMARY KEY)
SELECT (lcTable)
DBSETPROP(lcTable + ".ID", "FIELD", "Caption", "學號")
FOR lnIndex = 1 TO ALEN(taSubjects, 1)
taSubjects[lnIndex].Add_Column
NEXT
RAND(-1)
FOR lnRecord = 1 TO 1000
INSERT INTO &lcTable (ID) VALUES (TRANSFORM(lnRecord, "@L" + REPLICATE("9", 10)))
FOR lnIndex = 1 TO ALEN(taSubjects, 1) / 2
lcField = taSubjects[lnIndex].Title
REPLACE &lcField WITH RAND() * 100
NEXT
NEXT
USE IN "Scores"
SET DATABASE TO "Test"
CLOSE DATABASES
ENDPROC
PROCEDURE Do_Sort(taSubjects)
LOCAL lnIndex, lcScoreField, lcRankField, lnRank
OPEN DATABASE "Test"
USE "Scores" IN 0
SELECT "Scores"
FOR lnIndex = 1 TO ALEN(taSubjects, 1) / 2
lcScoreField = taSubjects[lnIndex].Title
lcRankField = taSubjects[lnIndex + ALEN(taSubjects, 1) / 2].Title
SET ORDER TO TAG &lcScoreField
GOTO TOP
lnRank = 0
SCAN ALL
lnRank = lnRank + 1
REPLACE &lcRankField WITH lnRank
ENDSCAN
NEXT
SET ORDER TO TAG ID
GOTO TOP
BROWSE
USE IN "Scores"
SET DATABASE TO "Test"
CLOSE DATABASES
ENDPROC
DEFINE CLASS myField AS Custom
Caption = "" && 標題
Title = "" && 字段名
Type = "" && 字段類型
Width = 0 && 字段寬度
Precision = 0 && 字段小數點位數
IsIndex = .F. && 是否索引字段
Ascend = 1 && 排序方向（1:升序，0:降序）
PROCEDURE Init(tcCaption, tcName, tcType, tnWidth, tnPrecision, tlIndex, tnAscend)
WITH This
.Caption = tcCaption
.Title = tcName
.Type = UPPER(tcType)
.Width = IIF(!EMPTY(tnWidth), tnWidth, 0)
.Precision = IIF(!EMPTY(tnPrecision), tnPrecision, 0)
IF VARTYPE(tlIndex) == "L"
.IsIndex = tlIndex
ENDIF
IF VARTYPE(tnAscend) == "N"
.Ascend = IIF(tnAscend != 0, 1, 0)
ENDIF
ENDWITH
ENDPROC
*------------------------
* 將字段添加到指定別名的表結構中
*------------------------
PROCEDURE Add_Column()
LOCAL lcDBF, lcString, lcTag
lcDBF = JUSTSTEM(DBF())
WITH This
IF TYPE(.Name) == "U"
lcString = .Title + " " + .Type
DO CASE
CASE INLIST(UPPER(.Type), "C", "Q", "V")
lcString = lcString + "(" + TRANSFORM(.Width) + ")"
CASE INLIST(UPPER(.Type), "N", "F")
lcString = lcString + "(" + TRANSFORM(.Width) + "," + TRANSFORM(.Precision) + ")"
CASE UPPER(.Type) == "B"
lcString = lcString + "(" + TRANSFORM(.Precision) + ")"
ENDCASE
ALTER TABLE &lcDBF ADD COLUMN &lcString
DBSETPROP(lcDBF + "." + .Title, "FIELD", "Caption", .Caption)
IF .IsIndex
lcTag = .Title
IF .Ascend == 1
INDEX ON &lcTag TAG &lcTag COLLATE "MACHINE" ASCENDING
ELSE
INDEX ON &lcTag TAG &lcTag COLLATE "MACHINE" DESCENDING
ENDIF
ENDIF
ENDIF
ENDWITH
ENDPROC
ENDDEFINE
