Question

frmAdd f = new frmAdd（）; string connectionString =（“Server =（localdb）\ v11.0; AttachDbFileName =”+ Application.StartupPath +“\ Database \”+ f.databaseName +“。mdf; Connect Timeout = 30;”）; SqlConnection connection = new SqlConnection（connectionString）;

        //notes=error, id and group=no like
        string selectCommand = "SELECT * FROM ContactsList WHERE " +
                "NamePrefix LIKE @prefix AND GivenName LIKE @given AND MiddleName LIKE @middle AND FamilyName LIKE @family AND " +
                "NameSuffix LIKE @suffix AND NickName LIKE @nick AND Company LIKE @company AND JobTitle LIKE @job AND " +
                "MobilePhone LIKE @mobilep AND HomePhone LIKE @homep AND WorkPhone LIKE @workp AND WorkFaxPhone LIKE @workfp AND HomeFaxPhone LIKE @homefp AND " +
                "PagerPhone LIKE @pagerp AND CallBackPhone LIKE @callbp AND OtherPhone LIKE @otherp AND GroupName=@group AND Relationship LIKE @relation AND " +
                "StreetHome LIKE @strh AND CityHome LIKE @cityh AND StateHome LIKE @stah AND ZipCodeHome LIKE @ziph AND CountryHome LIKE @countryh AND " +
                "StreetWork LIKE @strw AND CityWork LIKE @cityw AND StateWork LIKE @staw AND ZipCodeWork LIKE @zipw AND CountryWork LIKE @countryw AND " +
                "StreetOther LIKE @stro AND CityOther LIKE @cityo AND StateOther LIKE @stao AND ZipCodeOther LIKE @zipo AND CountryOther LIKE @countryo AND " +
                "HomeMail LIKE @homem AND WorkMail LIKE @workm AND OtherMail LIKE @otherm AND Website1 LIKE @web1 AND Website2 LIKE @web2 AND Website3 LIKE @web3 AND " +
                "Facebook LIKE @face AND GooglePlus LIKE @google AND BirthdayEvent LIKE @birth AND AnniversaryEvent LIKE @anni AND OtherEvent LIKE @othere";

        SqlCommand command1 = new SqlCommand(selectCommand);
        command1.Connection = connection;
        command1.CommandType = CommandType.Text;

        //if (!string.IsNullOrWhiteSpace(txtId.Text))
        //{
        //    command1.Parameters.AddWithValue("@id", txtId.Text);
        //}
        //else
        //{
        //    command1.Parameters.AddWithValue("@id", "%%");
        //}

        if (!string.IsNullOrWhiteSpace(txtPrefix.Text))
        {
            command1.Parameters.AddWithValue("@prefix", "%" + txtPrefix.Text + "%");
        }
        else
        {
            command1.Parameters.AddWithValue("@prefix", "%%");
        }

        if (!string.IsNullOrWhiteSpace(txtGiven.Text))
        {
            command1.Parameters.AddWithValue("@given", "%" + txtGiven.Text + "%");
        }
        else
        {
            command1.Parameters.AddWithValue("@given", "%%");
        }

。。。。。 .. .. 。。等等

Answer 1

SqlCommand command1 = new SqlCommand("SELECT * FROM ContactsList WHERE ID LIKE @id");

Answer 2

另一种方式：

     SqlCommand command1 = null;

    if (!string.IsNullOrWhiteSpace(txtId.Text))
    {
       command1 = new SqlCommand("SELECT * FROM ContactsList WHERE ID = @id");
       command1.Parameters.AddWithValue("@id", txtId.Text);
    }
    else
    {
       command1 = new SqlCommand("SELECT * FROM ContactsList ");
    }

    command1.Connection = connection;
    command1.CommandType = CommandType.Text;

Answer 3

试试这个：它取决于表[“server”]的列[“代码”]的数据类型。

如果Data-Type是Int / Numeric，那么下面的代码应该可以工作。

cmd.CommandText = "SELECT name FROM server WHERE code="+TextBox1.Text;

如果Data-Type是Varchar / Non-Numeric，请尝试如下。

cmd.CommandText = "SELECT name FROM server WHERE code='" + TextBox1.Text + "'";

但是，我不建议您进行内联查询。而是使用参数化查询。因为普通内联查询是SQL注入的邀请。

string sqlConnectString = "YourConnectionString";
string sqlSelect = "SELECT name FROM server WHERE code= @CodeValue";

SqlConnection sqlConnection = new SqlConnection(sqlConnectString);
SqlCommand sqlCommand = new SqlCommand(sqlSelect, sqlConnection);

sqlCommand.Parameters.Add("@CodeValue", System.Data.SqlDbType.Int);// Set SqlDbType based on your DB column Data-Type

 sqlCommand.Parameters["@CodeValue"].Value = TextBox1.Text;

SqlDataAdapter sqlDa = new SqlDataAdapter(sqlCommand);
DataTable sqlDt = new DataTable();
sqlDa.Fill(sqlDt);

this is a short tuto to help

如何从表中选择具有所有字段值的记录

3 个答案: