异步

描述

Dapper还使用了Async（异步）方法扩展了IDbConnection接口：

ExecuteAsync
QueryAsync
QueryFirstAsync
QueryFirstOrDefaultAsync
QuerySingleAsync
QuerySingleOrDefaultAsync
QueryMultipleAsync

我们只在本教程中添加了非异步版本，以便于阅读。

ExecuteAsync

var sql = "Invoice_Insert";
using (var connection = My.ConnectionFactory())
{ 
    connection.Open();
    var affectedRows = connection.ExecuteAsync(sql,
            new { Kind = InvoiceKind.WebInvoice, Code = "Single_Insert_1"},
            commandType: CommandType.StoredProcedure)
        .Result;
}

QueryAsync

var sql = "Invoice_Insert";
using (var connection = My.ConnectionFactory())
{ 
    connection.Open();
    var invoices = connection.QueryAsync<Invoice>(sql).Result.ToList();
}

QueryFirstAsync

var sql = "SELECT * FROM Invoice WHERE InvoiceID = @InvoiceID;";
using (var connection = My.ConnectionFactory())
{ 
    connection.Open();
    var invoice = connection.QueryFirstAsync<Invoice>(sql, new { InvoiceID = 1}).Result;
}

QueryFirstOrDefaultAsync

var sql = "SELECT * FROM Invoice WHERE InvoiceID = @InvoiceID;";
using (var connection = My.ConnectionFactory())
{ 
    connection.Open();
    var invoice = connection.QueryFirstOrDefaultAsync<Invoice>(sql, new { InvoiceID = 1}).Result;
}

QuerySingleAsync

var sql = "SELECT * FROM Invoice WHERE InvoiceID = @InvoiceID;";
using (var connection = My.ConnectionFactory())
{ 
    connection.Open();
    var invoice = connection.QuerySingleAsync<Invoice>(sql, new { InvoiceID = 1}).Result;
}

QuerySingleOrDefaultAsync

var sql = "SELECT * FROM Invoice WHERE InvoiceID = @InvoiceID;";
using (var connection = My.ConnectionFactory())
{ 
    connection.Open();
    var invoice = connection.QuerySingleOrDefaultAsync<Invoice>(sql, new { InvoiceID = 1}).Result;
}

QueryMultipleAsync

var sql = "SELECT * FROM Invoice; SELECT * FROM InvoiceItem;";
using (var connection = My.ConnectionFactory())
{ 
    connection.Open();
    using (var multi = connection.QueryMultipleAsync(sql, new {  InvoiceID = 1 }).Result)
    { 
        var invoice = multi.Read<Invoice>().First();
        var invoiceItems = multi.Read<InvoiceItem>().ToList();
    }
}

缓冲

描述

默认值：True

缓冲查询一次返回整个读取器，这在大多数情况下是理想的。

非缓冲查询与流式传输等效，您只需按需加载对象，这对于一个非常大的查询来减少内存使用情况可能很有用。

string sqlInvoices = "SELECT * FROM Invoice;";
using (var connection = My.ConnectionFactory())
{ 
    var invoices = connection.Query<Invoice>(sqlInvoices, buffered: false).ToList();
}

事务

描述

Dapper支持事务和范围事务。

事务

从连接开始一个新事务，并将其传递给事务可选参数。

var sql = "Invoice_Insert";
using (var connection = My.ConnectionFactory())
{ 
    connection.Open();
    using (var transaction = connection.BeginTransaction())
    { 
        var affectedRows = connection.Execute(sql,
            new { Kind = InvoiceKind.WebInvoice, Code = "Single_Insert_1"},
            commandType: CommandType.StoredProcedure,
            transaction: transaction);
        transaction.Commit();
    }
}

范围事务

在开始连接之前开始一个新的范围事务。

// 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();
}

存储过程

描述

在Dapper中使用存储过程非常简单，你只需要指定命令类型。

执行单个

执行一个存储过程。

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);
}

执行多个

执行多个存储过程。

var sql = "Invoice_Insert";
using (var connection = My.ConnectionFactory())
{ 
    connection.Open();
    var affectedRows = connection.Execute(sql,
        new[]
        { 
            new { Kind = InvoiceKind.WebInvoice, Code = "Many_Insert_1"},
            new { Kind = InvoiceKind.WebInvoice, Code = "Many_Insert_2"},
            new { Kind = InvoiceKind.StoreInvoice, Code = "Many_Insert_3"}
        },
        commandType: CommandType.StoredProcedure
    );
    My.Result.Show(affectedRows);
}