Question

当我单击checkboxlist2项而不选择checkboxlist1项时，按钮搜索会出错。我认为checkboxlist2编码错误，请遵循以下代码：

protected void Page_Load(object sender, EventArgs e)
{
    if(!this.IsPostBack)
    {
        this.BindGrid();
    }

}

protected void Button1_Click(object sender, EventArgs e)
{

    this.BindGrid();
}

private void BindGrid()
{
    string conString = ConfigurationManager.ConnectionStrings["MyConnectionString"].ConnectionString;
    string query = "SELECT * FROM Table_RegistrationInfo WHERE true";
    string condition = string.Empty;
    foreach (ListItem item in CheckBoxList1.Items)
    {
        condition += item.Selected ? string.Format("'{0}',", item.Value) : "";
    }
    if (!string.IsNullOrEmpty(condition))
    {
        condition = string.Format(" AND Nationality in ({0})", condition.Substring(0, condition.Length - 1));
    }
    string condition2 = string.Empty;
    foreach (ListItem item in CheckBoxList2.Items)
    {
        condition2 += item.Selected ? string.Format("'{0}',", item.Value) : "";
    }
    if (!string.IsNullOrEmpty(condition2))
    {
        //condition = string.Format(" where Nationality in ({0})", condition.Substring(0, condition.Length - 1));
        condition2 = string.Format(" AND GivenName in ({0})", condition2.Substring(0, condition2.Length - 1));
    }
    SqlCommand cmd = new SqlCommand(query + condition + condition2); using (SqlConnection con = new SqlConnection(conString))
    {
        using (SqlDataAdapter sda = new SqlDataAdapter())
        {
            cmd.Connection = con; sda.SelectCommand = cmd;
            using (DataSet ds = new DataSet())
            {
                sda.Fill(ds);
                GridView2.DataSource = ds;
                GridView2.DataBind();
            }
        }
    }


}
protected void Select_Nationality(object sender, EventArgs e)
{
    this.BindGrid();
}
protected void Select_GivenName(object sender, EventArgs e)
{
    foreach(ListItem item in CheckBoxList1.Items)
    {
        if(item.Selected == true)
        {
            this.BindGrid();
        }
    }
}

我必须实现8个复选框列表以过滤到gridview。如果要实现任何其他简单的技术，我必须使用从3个表中过滤。

Answer 1

如果condition为空或空，则查询变为：

SELECT ... FROM ... AND ...

这是不正确的。

你可以通过制作你的＆＃34; base＆＃34;来解决它。查询如下：

SELECT ... FROM ... WHERE 1=1

然后将AND ...之类的内容添加到其中。然后您的查询变为（只有condition有效时：

SELECT ... FROM ... WHERE 1=1 AND condition

相当于

SELECT ... FROM ... WHERE condition

在您的情况下，请更改此内容：

string query = "SELECT * FROM Table_RegistrationInfo";

到

string query = "SELECT * FROM Table_RegistrationInfo WHERE 1=1 ";

并改变这一点：

condition = string.Format(" where Nationality in ({0})", condition.Substring(0, condition.Length - 1));

进入

condition = string.Format(" AND Nationality in ({0})", condition.Substring(0, condition.Length - 1));

Answer 2

修改你的代码。

    private void BindGrid()
    {
        string conString = ConfigurationManager.ConnectionStrings["MyConnectionString"].ConnectionString;
        string query = "SELECT * FROM Table_RegistrationInfo";
        string condition = string.Empty;
        foreach(ListItem item in CheckBoxList1.Items)
        {
            condition += item.Selected ? string.Format("'{0}',", item.Value) : "";
        }
        if(!string.IsNullOrEmpty(condition))
        {
            condition = string.Format(" where Nationality in ({0})", condition.Substring(0, condition.Length - 1));
        }
        string condition2 = string.Empty;
        foreach(ListItem item in CheckBoxList2.Items)
        {
            condition2 += item.Selected ? string.Format("'{0}',", item.Value) : "";
        }
        if(!string.IsNullOrEmpty(condition2))
        {
         if(!string.IsNullOrEmpty(condition))
            {
            condition+=" And ";
            }
       else {
            Condition +=" Where "
            }


  //condition = string.Format(" where Nationality in ({0})", condition.Substring(0, condition.Length - 1));
            condition2 = string.Format(" GivenName in ({0})", condition2.Substring(0, condition2.Length - 1));
        }
        SqlCommand cmd = new SqlCommand(query + condition + condition2);
        using(SqlConnection con = new SqlConnection(conString))
        {
            using(SqlDataAdapter sda = new SqlDataAdapter())
            {
                cmd.Connection = con;
                sda.SelectCommand = cmd;
                using(DataSet ds = new DataSet())
                {
                    sda.Fill(ds);
                    GridView2.DataSource = ds;
                    GridView2.DataBind();
                }
            }
        }

    }

查询中关键字“AND”附近的语法不正确

2 个答案: