Dapper official translation Tutorial 7: QuerySingleOrDefault Dapper method of (turn)

Dapper official translation Tutorial 7: QuerySingleOrDefault Dapper method of

February 28, 2019 10:36:17  Day_and_Night_2017  Reads: 86

 

QuerySingleOrDefault method described

 

QuerySingleOrDefault method is an extension method, it can be called IDbConnection object, you can execute a query, and mapped to the result. If only one value, this value is returned directly, if there is no value, return to the default value, if more than one value, an exception will occur.

You can be mapped type:

• Anonymous (anonymous type var)
• Strongly Typed (strongly typed)

 

The method may be used parameter QuerySingleOrDefault

 

Name	Description
sql	check sentence
param	parameter
transaction	Whether to open the transaction
commandTimeout	Timeout period
commandType	Command Type

 

Anonymous queries

 

string sql = "SELECT * FROM OrderDetails WHERE OrderDetailID = @OrderDetailID;";

using (var connection = new SqlCeConnection("Data Source=SqlCe_W3Schools.sdf"))
{
var orderDetail = connection.QuerySingleOrDefault(sql, new {OrderDetailID = 1});

FiddleHelper.WriteTable(orderDetail);
}

 

Strongly typed queries

 

string sql = "SELECT * FROM OrderDetails WHERE OrderDetailID = @OrderDetailID;";

using (var connection = new SqlCeConnection("Data Source=SqlCe_W3Schools.sdf"))
{
var orderDetail = connection.QuerySingleOrDefault<OrderDetail>(sql, new {OrderDetailID = 1});

FiddleHelper.WriteTable( new List<OrderDetail>() { orderDetail });
}