Comparison of two ways for C to access SQL Server database (SqlDataReader vs SqlDataAdapter)

1. Use SqlDataReader Reading data

public bool CheckResultFromDatabase(string guid)
{
    
	string connStr = "Data Source = localhost; Initial Catalog = TestDB; User ID = sa; Password = Abc12345";

	// Create connection
	SqlConnection Myconnect = new SqlConnection(connStr);
	Myconnect.Open();

	// Build up query
	StringBuilder sb = new StringBuilder();
	sb.Append($"select id, name from dbo.table_a where id = '{
      guid}';");
	sb.Append($"select student_id, student_name from dbo.student where student_name = 'zhangsan';");
	string sql = sb.ToString();
	SqlCommand sqlQuery = new SqlCommand(sql, Myconnect);
	
	int rowCount = 0;
	bool [] checkresult = {
     false, false };
	int expectedResultNum = 2;
	int currentResult = 0;

	using (SqlDataReader reader = sqlQuery.ExecuteReader())
	{
    
		do
		{
    
			rowCount = 0;
			while (reader.Read())
			{
    
				rowCount++;
			}
			if (rowCount == 1)
			{
    
				checkresult[currentResult++] = true;
				if (currentResult == expectedResultNum)
					break;
			}
		} while (reader.NextResult()); // go to result of next sql query
		reader.Close();
	}
	Myconnect.Close();   // close databse
	return checkresult[0] && checkresult[1];
}

2. Use SqlDataReader Reading data

public bool CheckResultFromDatabaseAdapter(string guid)
{
    
	string connStr = "Data Source = localhost; Initial Catalog = TestDB; User ID = sa; Password = Abc12345";
	bool resultConfig = false;
	bool resultSummary = false;

	using (SqlConnection conn = new SqlConnection(connStr))
	{
    
		string strSql = $"select id, name from dbo.table_a where id = '{
      guid}';";

		using (SqlDataAdapter adapter = new SqlDataAdapter(strSql, conn))
		{
    
			DataTable dt = new DataTable();
			adapter.Fill(dt);
			if (dt.Rows.Count == 1)
			{
    
				resultConfig = true;
			}
			//dt.Rows[0][1] //1st record 1st row
			//foreach (DataRow dataRow in dt.Rows)
			//{
    
			// Console.WriteLine(dataRow["SimulationId"]);
			//}
		}

		strSql = $"select student_id, student_name from dbo.student where student_name = 'zhangsan';";
		using (SqlDataAdapter adapter = new SqlDataAdapter(strSql, conn))
		{
    
			DataTable dt = new DataTable();
			adapter.Fill(dt);
			if (dt.Rows.Count == 1)
			{
    
				resultSummary = true;
			}
		}
	}
	return resultConfig & resultSummary;
}

3. Comparison of the two methods

The two pieces of code above , Function the same , namely ： Read data that meets a certain condition from two tables , If the respective record numbers are 1, Then return to true, Otherwise return to false.

SqlDataReader Is characterized by ：

• Multiple queries can be done at one time , It must also be done at one time . Unified return and pass NextResult() To switch to the next result set . The most obvious benefit of this is to reduce client and db server The number of interactions , In some cases, it can greatly improve the efficiency of the program .
• No, RowCount Properties or methods , If you want to know the number of records in a result set , You can only count by yourself after traversing . All in all , Not very friendly .

Finish the former ,SqlDataAdapter Of course, the characteristics of ：

• Interface is rich , For programmers , It's a lot easier .
• You can query multiple times , It helps to improve the readability of the program .