Question

我有一些我想知道的东西，我希望每个人都可以帮助我。所以这是我的问题，我怎样才能缩短我的代码。：）

If MetroTextBox1.Text = "" Then
            If MetroCheckBox1.Checked = True And MetroCheckBox2.Checked = False Then
                query = "select id, fname, mname, lname, dept, salary, ' ' as lengthservice from tbl_Employee where dresigned is null and " +
                        " (id like '%" & MetroTextBox1.Text & "%' or fname like '%" & MetroTextBox1.Text & "%' or mname like '%" & MetroTextBox1.Text & "%' or lname like '%" & MetroTextBox1.Text & "%' or dept like '%" & MetroTextBox1.Text & "%') "
                dt = c.GetDataTable(query)
            ElseIf MetroCheckBox2.Checked = True And MetroCheckBox1.Checked = False Then
                query = "select id, fname, mname, lname, dept, salary, ' ' as lengthservice from tbl_Employee where dresigned is not null and " +
                        " (id like '%" & MetroTextBox1.Text & "%' or fname like '%" & MetroTextBox1.Text & "%' or mname like '%" & MetroTextBox1.Text & "%' or lname like '%" & MetroTextBox1.Text & "%' or dept like '%" & MetroTextBox1.Text & "%') "
                dt = c.GetDataTable(query)
            ElseIf MetroCheckBox1.Checked = True And MetroCheckBox2.Checked = True Then
                query = "select id, fname, mname, lname, dept, salary from tbl_Employee" +
                        " where id like '%" & MetroTextBox1.Text & "%' or fname like '%" & MetroTextBox1.Text & "%' or mname like '%" & MetroTextBox1.Text & "%' or lname like '%" & MetroTextBox1.Text & "%' or dept like '%" & MetroTextBox1.Text & "%' "
                dt = c.GetDataTable(query)
            End If
        ElseIf MetroTextBox1.Text <> "" Then
            If MetroCheckBox1.Checked = True And MetroCheckBox2.Checked = False Then
                query = "select id, fname, mname, lname, dept, salary, ' ' as lengthservice from tbl_Employee where dresigned is null and " +
                        " (id like '%" & MetroTextBox1.Text & "%' or fname like '%" & MetroTextBox1.Text & "%' or mname like '%" & MetroTextBox1.Text & "%' or lname like '%" & MetroTextBox1.Text & "%' or dept like '%" & MetroTextBox1.Text & "%') "
                dt = c.GetDataTable(query)
            ElseIf MetroCheckBox2.Checked = True And MetroCheckBox1.Checked = False Then
                query = "select id, fname, mname, lname, dept, salary, ' ' as lengthservice from tbl_Employee where dresigned is not null and " +
                        " (id like '%" & MetroTextBox1.Text & "%' or fname like '%" & MetroTextBox1.Text & "%' or mname like '%" & MetroTextBox1.Text & "%' or lname like '%" & MetroTextBox1.Text & "%' or dept like '%" & MetroTextBox1.Text & "%') "
                dt = c.GetDataTable(query)
            ElseIf MetroCheckBox1.Checked = True And MetroCheckBox2.Checked = True Then
                query = "select id, fname, mname, lname, dept, salary from tbl_Employee" +
                        " where id like '%" & MetroTextBox1.Text & "%' or fname like '%" & MetroTextBox1.Text & "%' or mname like '%" & MetroTextBox1.Text & "%' or lname like '%" & MetroTextBox1.Text & "%' or dept like '%" & MetroTextBox1.Text & "%' "
                dt = c.GetDataTable(query)
            End If
        Else
            query = "select id, fname, mname, lname, dept, salary, ' ' as lengthservice from tbl_Employee where id = ''"
            dt = c.GetDataTable(query)
        End If

Answer 1

由于问题是关于缩短代码，请按照以下方式进行：

query = " (id like '%" & MetroTextBox1.Text & "%' or fname like '%" & MetroTextBox1.Text & "%' or mname like '%" & MetroTextBox1.Text & "%' or lname like '%" & MetroTextBox1.Text & "%' or dept like '%" & MetroTextBox1.Text & "%')"
If MetroTextBox1.Text = "" Then
    If MetroCheckBox1.Checked = True And MetroCheckBox2.Checked = False Then
        query = "select id, fname, mname, lname, dept, salary, ' ' as lengthservice from tbl_Employee where dresigned is null and" + query
    ElseIf MetroCheckBox2.Checked = True And MetroCheckBox1.Checked = False Then
        query = "select id, fname, mname, lname, dept, salary, ' ' as lengthservice from tbl_Employee where dresigned is not null and" + query
    ElseIf MetroCheckBox1.Checked = True And MetroCheckBox2.Checked = True Then
        query = "select id, fname, mname, lname, dept, salary from tbl_Employee where" + query
    End If
ElseIf MetroTextBox1.Text <> "" Then
    If MetroCheckBox1.Checked = True And MetroCheckBox2.Checked = False Then
        query = "select id, fname, mname, lname, dept, salary, ' ' as lengthservice from tbl_Employee where dresigned is null and" + query
    ElseIf MetroCheckBox2.Checked = True And MetroCheckBox1.Checked = False Then
        query = "select id, fname, mname, lname, dept, salary, ' ' as lengthservice from tbl_Employee where dresigned is not null and" + query
    ElseIf MetroCheckBox1.Checked = True And MetroCheckBox2.Checked = True Then
        query = "select id, fname, mname, lname, dept, salary from tbl_Employee where" + query
    End If
Else
    query = "select id, fname, mname, lname, dept, salary, ' ' as lengthservice from tbl_Employee where id = ''"
End If
dt = c.GetDataTable(query)

Answer 2

这是更好（和更短）的代码：

Dim t1 As String = MetroTextBox1.Text
Dim c1 As Boolean = MetroCheckBox1.Checked
Dim c2 As Boolean = MetroCheckBox2.Checked

Dim a, b As String
a = "select id, fname, mname, lname, dept, salary"
b = "(id like '%" & t1 & "%' or fname like '%" & t1 & "%' or mname like '%" & t1 & "%' or lname like '%" & t1 & "%' or dept like '%" & t1 & "%') "

If c1 And Not c2 Then
    query = a + ", ' ' as lengthservice from tbl_Employee where dresigned is null and " + b

ElseIf c2 And Not c1 Then
    query = a + ", ' ' as lengthservice from tbl_Employee where dresigned is not null and " + b

Else 'If c1 And c2 Then
    query = a + " from tbl_Employee where " + b

End If

dt = c.GetDataTable(query)

（很明显，永远不会调用最终的Else因为总是MetroTextBox1.Text =＆＃34;＆＃34;或MetroTextBox1.Text＆lt;＆gt;＆＃34;＆＃34;将是真的。）

但是，这里有一个注释。当MetroTextBox1.Text =＆＃34;＆＃34;时，b中指定的条件变为(id like '%%' or fname like '%%' or ...)，可以从查询中删除where 1=1之类的内容。但它不是基于您的原始代码。如果你愿意，我可以提供修改后的代码

Answer 3

由于问题是缩短代码，这里是没有If语句的简短解决方案

Dim query As String = 
    "SELECT id, fname, mname, lname, dept, salary, ' ' AS lengthservice
     FROM tbl_Employee
     WHERE (id LIKE @MetroTextBox1 
         OR fname LIKE '%" & MetroTextBox1.Text & "%'
         OR mname LIKE '%" & MetroTextBox1.Text & "%' 
         OR lname LIKE '%" & MetroTextBox1.Text & "%' 
         OR dept LIKE '%" & MetroTextBox1.Text & "%')"

Dim condition As New Dictionary(Of Byte, String) From
{
    {0, ""}, 'You don't have result for case False, False
    {1, " AND dresigned IS NULL"}, 'If MetroCheckBox1.Checked = True
    {2, " AND dresigned IS NOT NULL"}, 'If MetroCheckBox2.Checked = True
    {3, ""}  'Both Checkboxes are checked
}

Dim checkBox1 As Byte = Convert.ToByte(MetroCheckBox1)
Dim checkBox2 As Byte = Convert.ToByte(MetroCheckBox2) << 1
Dim selection As Byte = checkBox1 Or checkBox2

query = query & condition(selection)

dt = c.GetDataTable(query)

非常重要：使用SqlParameters将值传递给查询

参数可以帮助您避免Sql注入问题，也可以让您的查询运行得更快。

缩短我的ElseIf声明。怎么样？

3 个答案: