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C# learning: SqlCommand

case 1: return one row of data,
sqlCommand cm = new ...

int qty = (int)cm.ExecuteScalar();

case 2: return multiple rows of data
SqlDataReader dataReader = cm.ExectueReader(CommandBehavior.CloseConnection);

while(dataReader.read()){
    Console.Write(dataReader.getString(0)..)
}

dataReader.Close();
cm.Close();

Case 3: no return value(e.g. insert, update, delete operations)
cm.CommandText = ...
cm.CommandType = CommandType.StoreProcedure;
cm.Connect = cn;

cn.open();
int n = cm.ExecuteNonQuery();
cn.Close();

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