基于Dapper二次封装了一个易用的ORM工具类：SqlDapperUtil,把日常能用到的各种CRUD都进行了简化封装，让普通程序员只需关注业务即可，因为非常简单，故直接贴源代码，大家若需使用可以直接复制到项目中，该SqlDapperUtil已广泛用于公司项目中。
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using Dapper;
using System.Data;
using System.Data.Common;
using System.Reflection;
using System.IO;
using System.Collections.Concurrent;
using System.Data.SqlClient;
namespace Zuowj.Common
{
///
/// 基于Dapper的数据操作类封装的工具类
/// Author：左文俊
/// Date：2017/12/11
///
public class SqlDapperUtil
{
private static string dbConnectionStringConfigPath = null;
private readonly static ConcurrentDictionary dbConnNamesCacheDic = new ConcurrentDictionary();
private string dbConnectionName = null;
private string dbConnectionString = null;
private string dbProviderName = null;
private IDbConnection dbConnection = null;
private bool useDbTransaction = false;
private IDbTransaction dbTransaction = null;
#region 私有方法
private IDbConnection GetDbConnection()
{
bool needCreateNew = false;
if (dbConnection == null || string.IsNullOrWhiteSpace(dbConnection.ConnectionString))
{
needCreateNew = true;
}
else if (!MemoryCacheUtil.Contains(dbConnectionName))
{
needCreateNew = true;
}
if (needCreateNew)
{
dbConnectionString = GetDbConnectionString(dbConnectionName, out dbProviderName);
var dbProviderFactory = DbProviderFactories.GetFactory(dbProviderName);
dbConnection = dbProviderFactory.CreateConnection();
dbConnection.ConnectionString = dbConnectionString;
}
if (dbConnection.State == ConnectionState.Closed)
{
dbConnection.Open();
}
return dbConnection;
}
private string GetDbConnectionString(string dbConnName, out string dbProviderName)
{
//如果指定的连接字符串配置文件路径，则创建缓存依赖，一旦配置文件更改就失效，再重新读取
string[] connInfos = MemoryCacheUtil.GetOrAddCacheItem(dbConnName, () =>
{
var connStrSettings = ConfigUtil.GetConnectionStringForConfigPath(dbConnName, SqlDapperUtil.DbConnectionStringConfigPath);
string dbProdName = connStrSettings.ProviderName;
string dbConnStr = connStrSettings.ConnectionString;
//LogUtil.Info(string.Format("SqlDapperUtil.GetDbConnectionString>读取连接字符串配置节点[{0}]:{1},ProviderName:{2}", dbConnName, dbConnStr, dbProdName), "SqlDapperUtil.GetDbConnectionString");
return new[] { EncryptUtil.Decrypt(dbConnStr), dbProdName };
}, SqlDapperUtil.DbConnectionStringConfigPath);
dbProviderName = connInfos[1];
return connInfos[0];
}
private T UseDbConnection(Func queryOrExecSqlFunc)
{
IDbConnection dbConn = null;
try
{
Type modelType = typeof(T);
var typeMap = Dapper.SqlMapper.GetTypeMap(modelType);
if (typeMap == null || !(typeMap is ColumnAttributeTypeMapper))
{
Dapper.SqlMapper.SetTypeMap(modelType, new ColumnAttributeTypeMapper());
}
dbConn = GetDbConnection();
if (useDbTransaction && dbTransaction == null)
{
dbTransaction = GetDbTransaction();
}
return queryOrExecSqlFunc(dbConn);
}
catch
{
throw;
}
finally
{
if (dbTransaction == null && dbConn != null)
{
CloseDbConnection(dbConn);
}
}
}
private void CloseDbConnection(IDbConnection dbConn, bool disposed = false)
{
if (dbConn != null)
{
if (disposed && dbTransaction != null)
{
dbTransaction.Rollback();
dbTransaction.Dispose();
dbTransaction = null;
}
if (dbConn.State != ConnectionState.Closed)
{
dbConn.Close();
}
dbConn.Dispose();
dbConn = null;
}
}
///
/// 获取一个事务对象（如果需要确保多条执行语句的一致性，必需使用事务）
///
///
/// paramDic)
{
return new DynamicParameters(paramDic);
}
#endregion
public static string DbConnectionStringConfigPath
{
get
{
if (string.IsNullOrEmpty(dbConnectionStringConfigPath))//如果没有指定配置文件，则取默认的配置文件路径作为缓存依赖路径
{
dbConnectionStringConfigPath = BaseUtil.GetConfigPath();
}
return dbConnectionStringConfigPath;
}
set
{
if (!string.IsNullOrWhiteSpace(value) && !File.Exists(value))
{
throw new FileNotFoundException("指定的DB连接字符串配置文件不存在：" + value);
}
//如果配置文件改变，则可能导致连接字符串改变，故必需清除所有连接字符串的缓存以便后续重新加载字符串
if (!string.Equals(dbConnectionStringConfigPath, value, StringComparison.OrdinalIgnoreCase))
{
foreach (var item in dbConnNamesCacheDic)
{
MemoryCacheUtil.RemoveCacheItem(item.Key);
}
}
dbConnectionStringConfigPath = value;
}
}
public SqlDapperUtil(string connName)
{
dbConnectionName = connName;
if (!dbConnNamesCacheDic.ContainsKey(connName)) //如果静态缓存中没有，则加入到静态缓存中
{
dbConnNamesCacheDic[connName] = true;
}
}
///
/// 使用事务
///
public void UseDbTransaction()
{
useDbTransaction = true;
}
///
/// 获取一个值，param可以是SQL参数也可以是匿名对象
///
/// (string sql, object param = null, int? commandTimeout = null, CommandType? commandType = null)
{
return UseDbConnection((dbConn) =>
{
return dbConn.ExecuteScalar(sql, param, dbTransaction, commandTimeout, commandType);
});
}
///
/// 获取第一行的所有值，param可以是SQL参数也可以是匿名对象
///
///
///
///
///
///
/// GetFirstValues(string sql, object param = null, int? commandTimeout = null, CommandType? commandType = null)
{
return UseDbConnection((dbConn) =>
{
Dictionary firstValues = new Dictionary();
List indexColNameMappings = new List();
int rowIndex = 0;
using (var reader = dbConn.ExecuteReader(sql, param, dbTransaction, commandTimeout, commandType))
{
while (reader.Read())
{
if ((++rowIndex) > 1) break;
if (indexColNameMappings.Count == 0)
{
for (int i = 0; i < reader.FieldCount; i++)
{
indexColNameMappings.Add(reader.GetName(i));
}
}
for (int i = 0; i < reader.FieldCount; i++)
{
firstValues[indexColNameMappings[i]] = reader.GetValue(i);
}
}
reader.Close();
}
return firstValues;
});
}
///
/// 获取一个数据模型实体类，param可以是SQL参数也可以是匿名对象
///
/// (string sql, object param = null, int? commandTimeout = null, CommandType? commandType = null) where T : class
{
return UseDbConnection((dbConn) =>
{
return dbConn.QueryFirstOrDefault(sql, param, dbTransaction, commandTimeout, commandType);
});
}
///
/// 获取符合条件的所有数据模型实体类列表，param可以是SQL参数也可以是匿名对象
///
/// GetModelList(string sql, object param = null, bool buffered = true, int? commandTimeout = null, CommandType? commandType = null) where T : class
{
return UseDbConnection((dbConn) =>
{
return dbConn.Query(sql, param, dbTransaction, buffered, commandTimeout, commandType).ToList();
});
}
///
/// 获取符合条件的所有数据并根据动态构建Model类委托来创建合适的返回结果（适用于临时性结果且无对应的模型实体类的情况）
///
/// (Func, T> buildModelFunc, string sql, object param = null, bool buffered = true, int? commandTimeout = null, CommandType? commandType = null)
{
var dynamicResult = UseDbConnection((dbConn) =>
{
return dbConn.Query(sql, param, dbTransaction, buffered, commandTimeout, commandType);
});
return buildModelFunc(dynamicResult);
}
///
/// 获取符合条件的所有指定返回结果对象的列表(复合对象【如：1对多，1对1】)，param可以是SQL参数也可以是匿名对象
///
/// GetMultModelList(string sql, Type[] types, Func map, object param = null, bool buffered = true, string splitOn = "Id", int? commandTimeout = null, CommandType? commandType = null)
{
return UseDbConnection((dbConn) =>
{
return dbConn.Query(sql, types, map, param, dbTransaction, buffered, splitOn, commandTimeout, commandType).ToList();
});
}
///
/// 执行SQL命令（CRUD），param可以是SQL参数也可以是要添加的实体类
///
///
///
///
///
///
///
/// 批量转移数据(利用SqlBulkCopy实现快速大批量插入到指定的目的表及SqlDataAdapter的批量删除)
///
public bool BatchMoveData(string srcSelectSql, string srcTableName, List srcPrimarykeyParams, string destConnName, string destTableName)
{
using (SqlDataAdapter srcSqlDataAdapter = new SqlDataAdapter(srcSelectSql, GetDbConnectionString(dbConnectionName, out dbProviderName)))
{
DataTable srcTable = new DataTable();
SqlCommand deleteCommand = null;
try
{
srcSqlDataAdapter.AcceptChangesDuringFill = true;
srcSqlDataAdapter.AcceptChangesDuringUpdate = false;
srcSqlDataAdapter.Fill(srcTable);
if (srcTable == null || srcTable.Rows.Count <= 0) return true;
string notExistsDestSqlWhere = null;
string deleteSrcSqlWhere = null;
for (int i = 0; i < srcPrimarykeyParams.Count; i++)
{
string keyColName = srcPrimarykeyParams[i].ParameterName.Replace("@", "");
notExistsDestSqlWhere += string.Format(" AND told.{0}=tnew.{0}", keyColName);
deleteSrcSqlWhere += string.Format(" AND {0}=@{0}", keyColName);
}
string dbProviderName2 = null;
using (var destConn = new SqlConnection(GetDbConnectionString(destConnName, out dbProviderName2)))
{
destConn.Open();
string tempDestTableName = "#temp_" + destTableName;
destConn.Execute(string.Format("select top 0 * into {0} from {1}", tempDestTableName, destTableName));
string destInsertCols = null;
using (var destSqlBulkCopy = new SqlBulkCopy(destConn))
{
try
{
destSqlBulkCopy.BulkCopyTimeout = 120;
destSqlBulkCopy.DestinationTableName = tempDestTableName;
foreach (DataColumn col in srcTable.Columns)
{
destSqlBulkCopy.ColumnMappings.Add(col.ColumnName, col.ColumnName);
destInsertCols += "," + col.ColumnName;
}
destSqlBulkCopy.BatchSize = 1000;
destSqlBulkCopy.WriteToServer(srcTable);
}
catch (Exception ex)
{
//LogUtil.Error("SqlDapperUtil.BatchMoveData.SqlBulkCopy:" + ex.ToString(), "SqlDapperUtil.BatchMoveData");
}
destInsertCols = destInsertCols.Substring(1);
destConn.Execute(string.Format("insert into {1}({0}) select {0} from {2} tnew where not exists(select 1 from {1} told where {3})",
destInsertCols, destTableName, tempDestTableName, notExistsDestSqlWhere.Trim().Substring(3)), null, null, 100);
}
destConn.Close();
}
deleteCommand = new SqlCommand(string.Format("DELETE FROM {0} WHERE {1}", srcTableName, deleteSrcSqlWhere.Trim().Substring(3)), srcSqlDataAdapter.SelectCommand.Connection);
deleteCommand.Parameters.AddRange(srcPrimarykeyParams.ToArray());
deleteCommand.UpdatedRowSource = UpdateRowSource.None;
deleteCommand.CommandTimeout = 200;
srcSqlDataAdapter.DeleteCommand = deleteCommand;
foreach (DataRow row in srcTable.Rows)
{
row.Delete();
}
srcSqlDataAdapter.UpdateBatchSize = 1000;
srcSqlDataAdapter.Update(srcTable);
srcTable.AcceptChanges();
return true;
}
catch (Exception ex)
{
//LogUtil.Error("SqlDapperUtil.BatchMoveData:" + ex.ToString(), "SqlDapperUtil.BatchMoveData");
return false;
}
finally
{
if (deleteCommand != null)
{
deleteCommand.Parameters.Clear();
}
}
}
}
///
/// 批量复制数据（把源DB中根据SQL语句查出的结果批量COPY插入到目的DB的目的表中）
///
public TResult BatchCopyData(string srcSelectSql, string destConnName, string destTableName, IDictionary colMappings, Func afterCoppyFunc)
{
using (SqlDataAdapter srcSqlDataAdapter = new SqlDataAdapter(srcSelectSql, GetDbConnectionString(dbConnectionName, out dbProviderName)))
{
DataTable srcTable = new DataTable();
TResult copyResult = default(TResult);
try
{
srcSqlDataAdapter.AcceptChangesDuringFill = true;
srcSqlDataAdapter.AcceptChangesDuringUpdate = false;
srcSqlDataAdapter.Fill(srcTable);
if (srcTable == null || srcTable.Rows.Count <= 0) return copyResult;
string dbProviderName2 = null;
using (var destConn = new SqlConnection(GetDbConnectionString(destConnName, out dbProviderName2)))
{
destConn.Open();
string tempDestTableName = "#temp_" + destTableName;
destConn.Execute(string.Format("select top 0 * into {0} from {1}", tempDestTableName, destTableName));
bool bcpResult = false;
using (var destSqlBulkCopy = new SqlBulkCopy(destConn))
{
try
{
destSqlBulkCopy.BulkCopyTimeout = 120;
destSqlBulkCopy.DestinationTableName = tempDestTableName;
foreach (var col in colMappings)
{
destSqlBulkCopy.ColumnMappings.Add(col.Key, col.Value);
}
destSqlBulkCopy.BatchSize = 1000;
destSqlBulkCopy.WriteToServer(srcTable);
bcpResult = true;
}
catch (Exception ex)
{
//LogUtil.Error("SqlDapperUtil.BatchMoveData.SqlBulkCopy:" + ex.ToString(), "SqlDapperUtil.BatchMoveData");
}
}
if (bcpResult)
{
copyResult = afterCoppyFunc(destConn);
}
destConn.Close();
}
return copyResult;
}
catch (Exception ex)
{
//LogUtil.Error("SqlDapperUtil.BatchCopyData:" + ex.ToString(), "SqlDapperUtil.BatchCopyData");
return copyResult;
}
}
}
///
/// 当使用了事务，则最后需要调用该方法以提交所有操作
///
///
public void Commit()
{
try
{
if (dbTransaction.Connection != null && dbTransaction.Connection.State != ConnectionState.Closed)
{
dbTransaction.Commit();
}
}
catch
{
throw;
}
finally
{
if (dbTransaction.Connection != null)
{
CloseDbConnection(dbTransaction.Connection);
}
dbTransaction.Dispose();
dbTransaction = null;
useDbTransaction = false;
if (dbConnection != null)
{
CloseDbConnection(dbConnection);
}
}
}
///
/// 当使用了事务，如果报错或需要中断执行，则需要调用该方法执行回滚操作
///
///
public void Rollback()
{
try
{
if (dbTransaction.Connection != null && dbTransaction.Connection.State != ConnectionState.Closed)
{
dbTransaction.Rollback();
}
}
catch
{
throw;
}
finally
{
if (dbTransaction.Connection != null)
{
CloseDbConnection(dbTransaction.Connection);
}
dbTransaction.Dispose();
dbTransaction = null;
useDbTransaction = false;
}
}
~SqlDapperUtil()
{
try
{
CloseDbConnection(dbConnection, true);
}
catch
{ }
}
}
}
ColumnAttributeTypeMapper辅助类相关代码如下：(如果不考虑实体类的属性与表字段不一致的情况，如下映射类可以不需要添加，同时SqlDapperUtil中移除相关依赖ColumnAttributeTypeMapper逻辑即可)
using Dapper;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Reflection;
using System.Text;
using System.Threading.Tasks;
namespace KYExpress.Common
{
public class ColumnAttributeTypeMapper : FallbackTypeMapper
{
public ColumnAttributeTypeMapper()
: base(new SqlMapper.ITypeMap[]
{
new CustomPropertyTypeMap(
typeof(T),
(type, columnName) =>
type.GetProperties().FirstOrDefault(prop =>
prop.GetCustomAttributes(false)
.OfType()
.Any(attr => attr.Name == columnName)
)
),
new DefaultTypeMap(typeof(T))
})
{
}
}
[AttributeUsage(AttributeTargets.Property, AllowMultiple = true)]
public class ColumnAttribute : Attribute
{
public string Name { get; set; }
}
public class FallbackTypeMapper : SqlMapper.ITypeMap
{
private readonly IEnumerable _mappers;
public FallbackTypeMapper(IEnumerable mappers)
{
_mappers = mappers;
}
public ConstructorInfo FindConstructor(string[] names, Type[] types)
{
foreach (var mapper in _mappers)
{
try
{
ConstructorInfo result = mapper.FindConstructor(names, types);
if (result != null)
{
return result;
}
}
catch (NotImplementedException)
{
}
}
return null;
}
public SqlMapper.IMemberMap GetConstructorParameter(ConstructorInfo constructor, string columnName)
{
foreach (var mapper in _mappers)
{
try
{
var result = mapper.GetConstructorParameter(constructor, columnName);
if (result != null)
{
return result;
}
}
catch (NotImplementedException)
{
}
}
return null;
}
public SqlMapper.IMemberMap GetMember(string columnName)
{
foreach (var mapper in _mappers)
{
try
{
var result = mapper.GetMember(columnName);
if (result != null)
{
return result;
}
}
catch (NotImplementedException)
{
}
}
return null;
}
public ConstructorInfo FindExplicitConstructor()
{
return _mappers
.Select(mapper => mapper.FindExplicitConstructor())
.FirstOrDefault(result => result != null);
}
}
}
使用示例方法如下：
1.先来模拟各种查询数据（由于是直接写模拟SQL输出，故没有条件，也便于大家COPY后直接可以测试结果）
//实例化SqlDapperUtil对象，构造函数是config文件中的connectionStrings的Name名
var dapper = new SqlDapperUtil("LmsConnectionString");
//查询1个值
DateTime nowTime = dapper.GetValue("select getdate() as nowtime");
//查询1行值，并转换成字典（这对于临时查询多个字段而无需定义实体类有用）
Dictionary rowValues = dapper.GetFirstValues("select 0 as col0,1 as col1,2 as col2");
//查询1行并返回实体类
Person person = dapper.GetModel("select '张三' as Name,22 as Age,'2018-1-1' as BirthDay,'中国广东深圳' as HomeAddr");
//查询1行表字段与实体类属性不一致映射
Person person2 = dapper.GetModel("select '张三' as Name,22 as Age,'2018-1-1' as BirthDay,'中国广东深圳' as HomeAddress");
//查询多行返回实体集合
var persons = dapper.GetModelList(@"select '张三' as Name,22 as Age,'2018-1-1' as BirthDay,'中国广东深圳' as HomeAddr union all
select '李四' as Name,25 as Age,'2018-10-1' as BirthDay,'中国广东深圳' as HomeAddress union all
select '王五' as Name,35 as Age,'1982-10-1' as BirthDay,'中国广东广州' as HomeAddress
");
//查询多行返回1对1关联实体结果集
var personWithCarResult = dapper.GetMultModelList(@"select t1.*,t2.* from
(select '张三' as Name,22 as Age,'2018-1-1' as BirthDay,'中国广东深圳' as HomeAddr union all
select '李四' as Name,25 as Age,'2018-10-1' as BirthDay,'中国广东深圳' as HomeAddress union all
select '王五' as Name,35 as Age,'1982-10-1' as BirthDay,'中国广东广州' as HomeAddress)as t1 inner join
(
select '张三' as DriverName,'大众' as Brand,'2018-8-8' as ManufactureDate union all
select '李四' as DriverName,'奔驰' as Brand,'2018-1-8' as ManufactureDate union all
select '王五' as DriverName,'奥迪' as Brand,'2017-8-8' as ManufactureDate
)as t2
on t1.Name=t2.DriverName
", new[] { typeof(Person), typeof(CarInfo) }, (objs) =>
{
Person personItem = objs[0] as Person;
CarInfo carItem = objs[1] as CarInfo;
personItem.Car = carItem;
return personItem;
}, splitOn: "DriverName");
//查询多行返回1对多关联实体结果=personWithManyCars
List personWithManyCars = new List();
dapper.GetMultModelList(@"select t1.*,t2.* from
(select '张三' as Name,22 as Age,'2018-1-1' as BirthDay,'中国广东深圳' as HomeAddr union all
select '李四' as Name,25 as Age,'2018-10-1' as BirthDay,'中国广东深圳' as HomeAddress union all
select '王五' as Name,35 as Age,'1982-10-1' as BirthDay,'中国广东广州' as HomeAddress)as t1 inner join
(
select '张三' as DriverName,'大众' as Brand,'2018-8-8' as ManufactureDate union all
select '张三' as DriverName,'奔驰' as Brand,'2018-1-8' as ManufactureDate union all
select '张三' as DriverName,'奥迪' as Brand,'2017-8-8' as ManufactureDate
)as t2
on t1.Name=t2.DriverName
", new[] { typeof(Person), typeof(CarInfo) }, (objs) =>
{
Person personItem = objs[0] as Person;
CarInfo carItem = objs[1] as CarInfo;
Person personItemMain = personWithManyCars.FirstOrDefault(p => p.Name == personItem.Name);
if (personItemMain == null)
{
personItem.Cars = new List();
personItemMain = personItem;
personWithManyCars.Add(personItemMain);
}
personItemMain.Cars.Add(carItem);
return personItemMain;
}, splitOn: "DriverName");
2.下面是演示如何进行增、删、改以及动态查询的情况：
//使用事务创建多张表，多条SQL语句写在一起
try
{
dapper.UseDbTransaction();
dapper.ExecuteCommand(@"create table T_Person(Name nvarchar(20) primary key,Age int,BirthDay datetime,HomeAddress nvarchar(200));
create table T_CarInfo(DriverName nvarchar(20) primary key,Brand nvarchar(50),ManufactureDate datetime)");
dapper.Commit();
}
catch (Exception ex)
{
dapper.Rollback();
//记日志
}
//使用事务批量插入多张表的多个记录，多条SQL分多次执行（参数支持批量集合对象传入，无需循环）
try
{
dapper.UseDbTransaction();
dapper.ExecuteCommand(@"insert into T_Person
select N'张三' as Name,22 as Age,'2018-1-1' as BirthDay,N'中国广东深圳' as HomeAddress union all
select N'李四' as Name,25 as Age,'2018-10-1' as BirthDay,N'中国广东深圳' as HomeAddress union all
select N'王五' as Name,35 as Age,'1982-10-1' as BirthDay,N'中国广东广州' as HomeAddress");
var carInfos = dapper.GetModelList(@"
select N'张三' as DriverName,N'大众' as Brand,'2018-8-8' as ManufactureDate union all
select N'李四' as DriverName,N'奔驰' as Brand,'2018-1-8' as ManufactureDate union all
select N'王五' as DriverName,N'奥迪' as Brand,'2017-8-8' as ManufactureDate");
dapper.ExecuteCommand(@"insert into T_CarInfo(DriverName,Brand,ManufactureDate) Values(@DriverName,@Brand,@ManufactureDate)", carInfos);
dapper.Commit();
}
catch (Exception ex)
{
dapper.Rollback();
//记日志
}
//执行删除，有参数，参数可以是实体类、匿名对象、字典（如有需要，可以是集合，以支持批量操作）
bool deleteResult = dapper.ExecuteCommand("delete from T_CarInfo where DriverName=@DriverName", new { DriverName = "李四" });
//构建动态执行SQL语句（以下是更新，查询类似）
StringBuilder updateSqlBuilder = new StringBuilder();
var updateParams = new Dictionary();
if (1 == 1)
{
updateSqlBuilder.Append(",Age=@Age");
updateParams["Age"] = 20;
}
if (2 == 2)
{
updateSqlBuilder.Append(",BirthDay=@BirthDay");
updateParams["BirthDay"] = Convert.ToDateTime("2010-1-1");
}
if (3 == 3)
{
updateSqlBuilder.Append(",HomeAddress=@HomeAddress");
updateParams["HomeAddress"] = "中国北京天安门";
}
string updateSql = string.Concat("update T_Person set ", updateSqlBuilder.ToString().TrimStart(','), " where Name=@Name");
updateParams["Name"] = "张三";
bool updateResult = dapper.ExecuteCommand(updateSql, updateParams);
//查询返回动态自定义结果，之所以不直接返回Dynamic就好，是因为可读性差，故尽可能的在执行后就转成指定的类型
Tuple hasCarInfo = dapper.GetDynamicModel>((rs) =>
{
var result = rs.First();
return Tuple.Create(result.Name, result.CarCount);
}, @"select a.Name,count(b.DriverName) as CarCount from T_Person a left join T_CarInfo b on a.Name=b.DriverName where a.Name=@Name group by a.Name", new { Name = "张三" });
3.还有两个方法：BatchCopyData、BatchMoveData，这是特殊封装的，不是基于Dapper而是基于原生的Ado.net及BCP，目的是快速大量跨DB跨表COPY数据或转移数据，使用也不复杂，建议想了解的网友可以查看我以往的文章
以上示例方法用到了两个类，如下：
class Person
{
public string Name { get; set; }
public int Age { get; set; }
public DateTime BirthDay { get; set; }
[Column(Name = "HomeAddress")]
public string HomeAddr { get; set; }
public CarInfo Car { get; set; }
public List Cars { get; set; }
}
class CarInfo
{
public string Brand { get; set; }
public DateTime ManufactureDate { get; set; }
public string DriverName { get; set; }
}
SqlDapperUtil类中依赖了之前我封装的类：如：MemoryCacheUtil(本地内存依赖缓存实用工具类)、ConfigUtil（配置文件管理工具类）、EncryptUtil（加密工具类），如果项目中不想引用这些类，可以移除或改成其它方法即可。
另外说明一下，为了防止和减少因DB连接未及时释放导致的连接池不足等原因，故默认执行所有的CRUD方法都是用完即释放，但有一种情况不会释放就是使用了事务，若使用事务，则必需配套使用：UseDbTransaction、Commit、或失败执行Rollback，否则可能导致未能及时释放对象，当然最终当SqlDapperUtil实例被回收后事务若没有提交或回滚，会强制执行回滚操作并释放事务及连接对象，防止可能的资源浪费情况。
本来早就想总结一下这篇文章，但一直由于工作太忙没有时间，今天利用加班研究.NET CORE的空隙时间完成，请大家支持，有好东西我一定会分享的，虽然不一定高大上，但一定实用且项目中有实战过的。