我正在尝试创建一个基于名称搜索动物的程序。我目前正在使用该部分，但是我想添加一个可选搜索，以便用户可以搜索特定数据，例如体重，组合框将显示所有具有匹配体重的动物的结果，用户可以然后选择他想要的，它会打开我设计的表格，显示正确的数据。不幸的是，我对编程有非常基本的了解，所以任何帮助都将不胜感激。
这是我当前的代码。主要搜索功能有效，但可选功能无效。有人告诉我这是由于我编写它的方式，因为每行 sql 都会替换自己，所以它只会以最后一个答案结束。
Private Sub btnsear_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnsear.Click
If (txtname.Text = "") Then
MsgBox("Invalid Search")
Else
Try
Dim newsql As String
newsql = "select * from Animals where AnimalName like " & "'%" & txtname.Text & "%'"
'MsgBox("select * from Animals where AnimalName like " & "'" & txtname.Text & "'")
'msgbox(newsql)
Dim con As New OleDb.OleDbConnection
Dim da As New OleDb.OleDbDataAdapter
' dim ds as NewDataTable
Dim dt As New DataTable("Animals")
' uses the 2010 compatible connection string
con.ConnectionString = "PROVIDER=Microsoft.ACE.OLEDB.12.0;Data Source = h:\Animals.accdb"
con.Open()
da = New OleDb.OleDbDataAdapter(newsql, con)
da.Fill(dt)
Form2.Show()
'show name in unbound text box
Form2.nametxt.Text = dt.Rows(0).Item(1)
Form2.latintxt.Text = dt.Rows(0).Item(2)
Form2.locationtxt.Text = dt.Rows(0).Item(3)
Form2.heighttxt.Text = dt.Rows(0).Item(4)
Form2.weighttxt.Text = dt.Rows(0).Item(5)
Form2.diettxt.Text = dt.Rows(0).Item(6)
Form2.statustxt.Text = dt.Rows(0).Item(7)
Form2.lifetxt.Text = dt.Rows(0).Item(8)
Form2.breedtxt.Text = dt.Rows(0).Item(9)
Form2.lengthtxt.Text = dt.Rows(0).Item(10)
Form2.txtimage.Text = dt.Rows(0).Item(11)
Catch
MsgBox("Item Not Found")
'con.close()
End Try
End If
If (txtopt.Text = "'") Then
Try
Dim sql1 As String
Dim sql2 As String
Dim sql3 As String
Dim sql4 As String
Dim sql5 As String
Dim sql6 As String
Dim sql7 As String
Dim sql8 As String
Dim sql9 As String
Dim sql10 As String
sql1 = "select * from Animals where AnimalName like " & "'%" & txtopt.Text & "%'"
sql2 = "select * from Animals where LatinName like " & "'%" & txtopt.Text & "%'"
sql3 = "select * from Animals where Location like " & "'%" & txtopt.Text & "%'"
sql4 = "select * from Animals where AverageHeight like " & "'%" & txtopt.Text & "%'"
sql5 = "select * from Animals where AverageWeight like " & "'%" & txtopt.Text & "%'"
sql6 = "select * from Animals where DietaryNeeds like " & "'%" & txtopt.Text & "%'"
sql7 = "select * from Animals where ConservationStatus like " & "'%" & txtopt.Text & "%'"
sql8 = "select * from Animals where AverageLifeSpan like " & "'%" & txtopt.Text & "%'"
sql9 = "select * from Animals where BreedingSeason like " & "'%" & txtopt.Text & "%'"
sql10 = "select * from Animals where AverageLength like " & "'%" & txtopt.Text & "%'"
Catch
End Try
End If
End Sub