SQL LIKE搜索多个文本框？

Posted 2021-04-02

这是我按钮的代码。

private void btnStudentLookup_Click(object sender, EventArgs e)
    {
        string strConnect = "Server=DESKTOP- 
        2Q73COU\SQLEXPRESS;Database=LoginApp;Trusted_Connection=True;";
        SqlConnection conn = new SqlConnection(strConnect);
        conn.Open();
        using (SqlConnection studentLookup = new SqlConnection(strConnect))
        {
            SqlCommand command =
                new SqlCommand("SELECT * FROM Main_Information WHERE [First Name] like '%" + txtFirstName.Text + "%';", studentLookup);

            SqlDataAdapter adapter = new SqlDataAdapter(command);
            DataTable dt = new DataTable();
            adapter.Fill(dt);
            dgvAdvisor.DataSource = dt;
        }
    }

以上一切都有效。它根据名字过滤出行。但是，我想过滤掉更多，所以我将其添加到该行：

"SELECT * FROM Main_Information WHERE [First Name] like '%" + txtFirstName.Text + "%' OR [Last Name] like '%" + txtLastName.Text + "%';", studentLookup

现在它什么也没做。没有错误，没有例外，没有。有什么建议？

答案

更改查询如下：

SELECT * FROM Main_Information WHERE [First Name]如'％'+ txtFirstName.Text +“％'AND [Last Name] like'％”+ txtLastName.Text +“％';”，studentLookup

使用AND运算符代替OR。

另一答案

在测试应用程序时，请在txtFirstName文本框中写入：

'; DELETE FROM Main_Information; --

然后按“提交”按钮。

如果一切正常那么好，如果没有那么使用SqlParameters来构建具有动态值的查询

using (var connection = new SqlConnection(connectionString))
using (var command = connection.CreateCommand())
{
    var query = @"
        SELECT * FROM Main_Information
        WHERE [First Name] LIKE @firstName AND [Last Name] LIKE @lastName";
    var parameters = new [] 
    {
        new SqlParameter
        {
            ParameterName = "@firstName",
            SqlDbType = SqlDbType.VarChar,
            Value = $"%{txtFirstName.Text}%"
        },
        new SqlParameter
        {
            ParameterName = "@lastName",
            SqlDbType = SqlDbType.VarChar,
            Value = $"%{txtLastName.Text}%"
        }
    }   

    command.CommandText = query;
    command.Parameters.AddRange(parameters);

    connection.Open();

    var adapter = new SqlDataAdapter(command);
    var data = new DataTable();
    adapter.Fill(data);
    dgvAdvisor.DataSource = data;
}