Dapper学习(三)之其他用法

这里说的其他用法，是指 Async,Buffered,Transaction,Stored Procedure。

1. 首先 dapper支持异步

ExecuteAsync, QueryAsync, QueryFirstAsync, QueryFirstOrDefaultAsync, QuerySingleAsync, QuerySingleOrDefaultAsync, QueryMultipleAsync 

ExecuteAsync 用法示例：

string sql = "INSERT INTO Customers (CustomerName) Values (@CustomerName);";

using (var connection = new SqlConnection(FiddleHelper.GetConnectionStringSqlServerW3Schools()))
{
    var affectedRows = connection.ExecuteAsync(sql, new {CustomerName = "Mark"}).Result;

    Console.WriteLine(affectedRows);

    var customer = connection.Query<Customer>("Select * FROM CUSTOMERS WHERE CustomerName = 'Mark'").ToList();

    FiddleHelper.WriteTable(customer);
}

2. Buffered

默认是：True

A buffered query return the entire reader at once. 

A non-bufferd query is equivalent as streaming. you only load objects on demand. That can be useful for a very large query to reduce memory usage. 

string sql = "SELECT * FROM OrderDetails;";

using (var connection = new SqlConnection(FiddleHelper.GetConnectionStringSqlServerW3Schools()))
{
    var orderDetails = connection.Query<OrderDetail>(sql, buffered: false).ToList();

    FiddleHelper.WriteTable(orderDetails.Take(10));
}

3. Transaction

dapper支持 transaction 和 TransactionScope

Transaction

使用示例如下：

string sql = "INSERT INTO Customers (CustomerName) Values (@CustomerName);";

using (var connection = new SqlConnection(FiddleHelper.GetConnectionStringSqlServerW3Schools()))
{
    connection.Open();
    
    using (var transaction = connection.BeginTransaction())
    {
        var affectedRows = connection.Execute(sql, new {CustomerName = "Mark"}, transaction: transaction);
        
        transaction.Commit();
        
        Console.WriteLine(affectedRows);
    }
}

TransactionScope

在连接之前，使用 transaction scope

// using System.Transactions;

using (var transaction = new TransactionScope())
{
    var sql = "Invoice_Insert";

    using (var connection = My.ConnectionFactory())
    {
        connection.Open();

        var affectedRows = connection.Execute(sql,
            new {Kind = InvoiceKind.WebInvoice, Code = "Single_Insert_1"},
            commandType: CommandType.StoredProcedure);
    }

    transaction.Complete();
}

4. Stored Procedure

在dapper中使用存储过程，只需要指定命令类型

var sql = "Invoice_Insert";

using (var connection = My.ConnectionFactory())
{
    connection.Open();

    var affectedRows = connection.Execute(sql,
        new {Kind = InvoiceKind.WebInvoice, Code = "Single_Insert_1"},
        commandType: CommandType.StoredProcedure);

    My.Result.Show(affectedRows);
}

dapper学习