基础·通过代码构建简单DW

[参考]：《Power Builder Help》(8.0)

Objects and Controls —— System Object Properties, Events, and Functions —— Transaction object

DataWindow Reference —— Methods for the DataWindow Control —— Create method

DataWindow Reference —— DataWindow Object Properties —— Controls in a DataWindow and their properties —— Properties for the DataWindow object

 

 

SyntaxFromSQL

Description: Generates DataWindow source code based on a SQL SELECT statement.

Syntax: transaction.SyntaxFromSQL(sqlselect,presentation,err)

Argument

transaction: The name of a connected transaction object

sqlselect: A string whose value is valid SQL SELECT statement

presentation: A string whose value is the default presentation style you want for the DatWindow.The simple format is: Style(Type=presentationstyle)

Keywords are: (Default) Tabular

                        Grid

                        Form(for freeform)

                        Graph

                        Group

                        Label

                        Nup

err: A string variable to which PowerBuilder will assign any error message that occur

Return value

string

""        —— error occurs

NULL   —— argument's value is NULL

 

 

Create method (DataWindows)

Description: Creates a DataWindow object using DataWindow source code and puts that object in the specified DataWindow control or DataStore object. This dynamic DataWindow object does not become a permanent part of the application source library.

Syntax: integer dwcontrol.Create(string syntax{,string errorbuffer})

Argument

syntax: A string whose value is the DataWindow source code that will be used to create the DataWindow object

errorbuffer: The name of a string that will hold any error message that occur.

 

 

Table.property

Description: Properties for the DataWindow's DBMS connection.

Syntax: dw_control.Object.DataWindow.Table.property

（表的属性很多，在此不列举，请参考帮助）

 

 

SetTransObject method (DataWindows)

Description: Causes a DataWindow control or DataStore to use a programer-specified transaction object.

Syntax: integer dwcontrol.SetTransObject(transaction transaction)

Return value

 1      —— succeeds

-1      —— error occurs

NULL —— argument's value is NULL

 

 

Retrieve method (DataWindows)

Description: Retrieves rows from the database for a DataWindow control or DataStore.

Syntax: long dwcontrol.Retrieve({any argument,any argument ...})

Return value

The number of rows displayed —— succeeds

-1                                             —— fails

 

 

[简单示例]：

string ls_sql,ls_err long ll_rows ls_sql = "select * from XXX" ls_sql = SQLCA.syntaxfromsql( ls_sql, "style(type=grid)", ls_err) if len(ls_err) > 0 then messagebox("取得SQL语法时出错",ls_err) return 0 else dw_1.create( ls_sql,ls_err) if len(ls_err) > 0 then messagebox("创建数据对象时出错",ls_err) return 0 end if dw_1.Object.DataWindow.Table.UpdateWhere = '0' dw_1.object.DataWindow.Table.UpdateKeyinPlace = 'yes' end if if dw_1.settransobject( SQLCA) = 1 then ll_rows = dw_1.retrieve( ) end if if ll_rows < 1 then messagebox('提示','不存在指定条件的记录!',StopSign!) end if