How to read specific column and cell in mysql in c#?

问题

I use ExecuteReader to select all (SELECT*) for all field like this

string query = "SELECT* FROM tb_patient_information ";
        if (this.OpenConnection() == true)
        { //Create Command
            MySqlCommand cmd = new MySqlCommand(query, connection);
            //Create a data reader and Execute the command
            MySqlDataReader dataReader = cmd.ExecuteReader();
            while (dataReader.Read())
            { ... }

but I only want to select in specific column and cell like in red square.. like this picture

回答1:

You can get the specific column inside the while clause.

while (dataReader.Read())
{ 
    var _column = dataReader["Nama_Kategori"];
}

回答2:

Consider using

        string query = "SELECT column FROM tb_patient_information ";
        if (this.OpenConnection() == true)
        { 
            //Create Command
            MySqlCommand cmd = new MySqlCommand(query, connection);
            //Create a data reader and Execute the command
            MySqlDataReader dataReader = cmd.ExecuteReader();
            if (dataReader.Read())
            { 
                dataReader.ExecuteScalar();
             }
        }

or use dataReader["columnName"]

回答3:

You can use ExecuteScalar() of MySqlCommand method to retieve single value

MySqlCommand myCommand = new MySqlCommand("SELECT Nama_Kategori FROM tb_patient_information WHERE Id_kategori = 'KI-02'", myConnection);
myCommand.Connection.Open();
myCommand.ExecuteScalar();
myConnection.Close();

回答4:

SQL Query

If you want only third row data then try the below query :

Select * from (Select row_number() over (order by subssn) as rownum, * FROM 
tb_patient_information)result Where rownum = 3

-This Query return the 3rd row on Result Set

In DataReader

while (dataReader.Read())
{ 
string Id = dataReader["Id_kategori"].ToString();
string Name = dataReader["Nama_Kategori"].ToString();
}

OR IF You Say I only use Select * from tb_patient_information and i need 3rd row result Then try like below

         int count=1;  
         while (dataReader.Read())  
          {  

            if(count == 3)
            {
             string Id = dataReader["Id_kategori"].ToString();
             string Name = dataReader["Nama_Kategori"].ToString();
            }  
           count ++;  
          }

来源：https://stackoverflow.com/questions/15904333/how-to-read-specific-column-and-cell-in-mysql-in-c

标签

mysql

select

executereader