Question

vb语言怎么实现access数据表中行与行间的运算？

就像这个数据我怎用VB实现求第二行减去上第三行求各个企业的净利润 然后输出

Answer 1

vb支持SQL查询语言，先添加部件 microsoft ado data control 6.0(oledb) ,然后再生成连接字符，也可以直接使用
Private strConn As String '连接字符串
Private StrSql As String, StrSql_Select As String, Strsql_Insert As String, Strsql_Update As String '定义SQL语句
Private conn As New ADODB.Connection '定义一个新的connection实例conn
Private rs, As New ADODB.Recordset '定义一个新的记录集Recordset实例rs
strConn = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" & Database_Path & "xxx.mdb;Persist Security Info=False;Jet OLEDB:DataBase Password=密码"'这个是ACCESS的连接字符串，Database_Path为数据库目录，XXX为数据库名称，记得不要忘记"\"，保证文件路径存在，
Set conn = New ADODB.Connection
conn.ConnectionString = strConn '连接数据库
conn.Open
dim maolirun ,chengben ,jinglirun as single
'中间是SQL语言,假如你数据库的表明是利润，假如需要合计那一列计算，就这样
StrSql_Select = "select 合 from 利润 where 指='一、毛利润'"
　Set rs = conn.Execute(StrSql_Select)
　maolirun=　val(rs(0))'也可以写成maolirun=　val(rs("合"))

StrSql_Select = "select 合 from 利润 where 指='二、成本'"
　Set rs = conn.Execute(StrSql_Select)
　chengben=　val(rs(0))'也可以写成maolirun=　val(rs("合"))
,jinglirun=maolirun-chengben
coon.close

Answer 2

先把每行的各字段值读出来，再对读取的值做数学运算。

追问

用数组读吗 大概的代码是咋样的呢

追答

Dim cnn As New ADODB.Connection
Dim redset As New ADODB.Recordset

'连接数据库，并打开数据库文件MDB

Private Sub OpenAccessdb(dbStr As String)
On Error GoTo ErrorProc
Set cnn = Nothing
cnn.ConnectionString = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" & App.Path & dbStr & ";Persist Security Info=False;Jet OLEDB:Database Password=audiodj"

cnn.Open
Exit Sub
ErrorProc:
If Err.Description "" Then
MsgBox Err.Description, vbCritical, "错误信息"
End If
End Sub
'处理数据表MDB
Private Sub OperateAccessDb(sqlStr As String)
On Error GoTo ErrorProc
Set redset = Nothing
Set redset.ActiveConnection = cnn
redset.CursorType = adOpenStatic
redset.LockType = adLockPessimistic
redset.Open sqlStr
Exit Sub
ErrorProc:
If Err.Description "" Then
MsgBox Err.Description, vbCritical, "错误"
End If
End Sub

Private Sub Command1_Click()
Dim cbValue(4) As Single
Dim mlrValue(4) As Single
OpenAccessdb "文件名.mdb"
OperateAccessDb "select * from 表名"
If redset.RecordCount > 0 Then
redset.MoveFirst
For i = 1 To redset.RecordCount
Select Case redset.Fields("指")
Case "一、毛利润"
mlrValue(0) = redset.Fields("合")
mlrValue(1) = redset.Fields("01")
mlrValue(2) = redset.Fields("02")
mlrValue(3) = redset.Fields("03")
mlrValue(4) = redset.Fields("04")
Case "二、成本"
cbValue(0) = redset.Fields("合")
cbValue(1) = redset.Fields("01")
cbValue(2) = redset.Fields("02")
cbValue(3) = redset.Fields("03")
cbValue(4) = redset.Fields("04")
End Select
redset.MoveNext
Next i
End If
'这后就可以计算 cbvalue和mlrvalue这两个数组变量的差值了。
End Sub