我喜欢用不同的公式填充我的数据库。
当我在数据库中有一个像"(2+4)*5"
这样的公式时,我得到的结果是40
update DB.dbo.INFOGROUP SET formula = '(2+4)*5' where INFOGROUP = 'S42'
当我在数据库中有一个像"(x+4)*5"
这样的公式时,我得到的结果是20
。即使我将x
的值设置为10
,也会忽略x
的值
update DB.dbo.INFOGROUP SET formula = '(x+4)*5' where INFOGROUP = 'S42'
Private Sub BtnCalculate_Click(sender As Object, e As EventArgs) Handles BtnCalculate.Click
Dim SC As New MSScriptControl.ScriptControl
Dim x As Double = 10
SQL.AddParam("@infogroup", "S42")
SQL.ExecQuery($"SELECT formula FROM DB.dbo.INFOGROEP where infogroep=@infogroep")
Dim Formula As String = <string_from_db>
'SET LANGUAGE TO VBSCRIPT
SC.Language = "VBSCRIPT"
'ATTEMPT MATH
Try
Dim Result As Double = Convert.ToDouble(SC.Eval(Formula))
'SHOW THAT IT WAS VALID
MessageBox.Show("Math success, " & Formula & " equals " & Result.ToString)
Catch ex As Exception
'SHOW THAT IT WAS INVALID
MessageBox.Show("Not a valid math formula for a double.")
End Try
End Sub
这是可能的吗,或者我需要一个第三方脚本吗?
顺便说一句:在Visual Foxpro中有一个类似EVAL(db_string)
的函数。
发布于 2018-10-08 01:31:19
脚本引擎对方法中的变量一无所知。如果要计算包含变量的公式,则需要告诉它该变量具有什么值:
SC.Language = "VBSCRIPT"
sc.AddCode "Private Const x = 10"
Dim Result As Double = Convert.ToDouble(SC.Eval(Formula))
https://stackoverflow.com/questions/52690844
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