确定选择了哪些组合框的提示？

Question

我在 Access 数据库中有 8 个组合框。每个组合框可以有一个值或没有一个值（2个选项）。总共可以有 256 种组合 (2^8)。我正在尝试在 VBA 中创建一些代码，循环遍历这些组合以确定当前存在的组合，最终目标是基于该组合在 VBA 中编写 SQL 查询。例如，假设combo1 和combo2 都有选择，但combo3 到combo8 没有。如果 是 的组合，我希望我的 SQL 查询执行 SELECT FROM 查询，其中 db = combo1 中的列和 db = combo2 中的列。任何人都可以提供有关我将如何构建代码的提示吗？

谢谢！

Answer 1

Dim a as string, b as string 
const myAND as string = "AND "

a = ""
a = "SELECT * FROM a table "

b = ""
if cbo1.value <> "" then
  b = b & myAND & "AND field1 = '" & cbo1.value & "'"
end if

if cbo2.value <> "" then
  b = b & myAND & "field2 = '" & cbo2.value & "'"
end if

etc for each cbo box

If b <> "" Then

   ' Lazy way 
   ' a = a & "WHERE 1=1 " & b 

   ' remove the first AND way
   a = a & "WHERE 1=1 " & mid(b,len(myAND))

End if

' a now contains the SQL you need.

Answer 2

Dim where_condtion as String
Dim sqlquery as String

where_condtion = ""

IF combo1 <>"" then
    where_condtion = where_condtion + "~fieldname~ = " & combo1
End IF
IF combo2 <>"" then
    where_condtion = where_condtion + "AND ~fieldname~ = " & combo2
End IF
*
*
*
IF combo8 <>"" then
    where_condtion = where_condtion + "AND ~fieldname~ =" & combo8
End IF

IF where_condtion <> "" then
    sqlquery = "Select * from ~table name~ where" + where_condtion
ELSE
    sqlquery = "Select * from ~table name~
End IF

sqlquery = Replace(sqlquery, "where AND ", "where ")

DoCmd.OpenQuery "sqlquery", acViewNormal, acEdit

OR

CurrentDb.OpenRecordset("sqlquery")

Answer 3

Am 选项将是一个连接字符串

代码示例

Dim strSQL as String
'basic string
strSQL = "SELECT tbl.fieldA, tbl.fieldB FROM tbl "

Dim strSQLwhere as String
strSQLwhere = ""
'Combobox cmbbox1
If Not isNull(cmbbox1) And cmbbox1.ListIndex <> -1 then
    strSQLwhere = strSQLwhere & "tbl.fieldToFilter1=" & cmbbox1
End if

'Combobox cmbbox2
If Not isNull(cmbbox2) And cmbbox2.ListIndex <> -1 then
    iF NOT strSQLwhere = "" then     
       strSQLwhere = strSQLwhere & " AND "
    end if
    strSQLwhere = strSQLwhere & "tbl.fieldToFilter2=" & cmbbox2
End if

'And so on until cmbBox 8

'Combine all Strings
if not strSQLwhere = "" then
    strSQL  = strSQL  & " WHERE (" & strSQLwhere & ")"
End if

'Add here further thing like ORDER BY, GROUP BY
'Show SQL sting if it is well fomratted, change string concatenation if not
debug.print strSQL  

如果您能够在 VBA 中执行此操作，您可以在单独的函数中执行组合框 if-then-(else) 案例。