ef 批量插入

项目数据库里已经有了省市数据，任务是导入县数据。其中省市县之间有外键关系。

public void ImportCounties(List<County> counties)

{

List<City> cities = counties.Select(d => d.City).ToList();

MyTestEntities db = new MyTestEntities();

foreach (var city in cities)

{

Province province =

db.Provinces.Where(d => d.Name == city.Province.Name).First();

city.Province = province;

}

foreach (var county in counties)

{

db.Counties.AddObject(county);

}

db.SaveChanges();

}

这是项目里的源代码，耗时40秒左右。我测试之后发现不仅效率低，而且是有bug的。测试时第一次录入数据没问题，如果删除Counties表里的数据再 导入数据是有问题的，我不知道为什么要为Province赋值而且第一次可以成功，如果有大神看见，请帮我解惑。我只能先尝试以我的方法去做。

public void ImportCountiesSecond(List<County> counties)

{

MyTestEntities db = new MyTestEntities();

List<City> cities = db.Cities.ToList();

foreach (var county in counties)

{

county.City = cities.Where(d => d.Name == county.City.Name).FirstOrDefault();

db.Counties.AddObject(county);

}

db.SaveChanges();

}

速度大概缩减到20秒，但这也不是我所能忍受的。于是上网又查了资料，了解到SqlBulkCopy。

代码如下：

public void ImportCountiesThird(List<County> counties)

{

MyTestEntities db = new MyTestEntities();

string conStr = ConfigurationManager.ConnectionStrings["dbConnStr"].ConnectionString;

List<City> cities = db.Cities.ToList();

DataTable table = new DataTable();

table.Columns.Add("CityId", typeof(int));

table.Columns.Add("Name");

table.Columns.Add("OrderNum", typeof(int));

table.Columns.Add("IsCity", typeof(bool));

for (int i = 0; i < counties.Count; i++)

{

County line = counties[i];

int cityId = cities.Where(d => d.Name == counties[i].City.Name).FirstOrDefault().CityId;

string name = line.Name;

int orderNum = line.OrderNum;

bool isCity = line.IsCity;

DataRow row = table.NewRow();

row["CityId"] = cityId;

row["Name"] = name;

row["OrderNum"] = orderNum;

row["IsCity"] = isCity;

table.Rows.Add(row);

}

using (SqlBulkCopy bulkCopy = new SqlBulkCopy(conStr))

{

bulkCopy.DestinationTableName = "Counties";

bulkCopy.ColumnMappings.Add("CityId", "CityId");

bulkCopy.ColumnMappings.Add("Name", "Name");

bulkCopy.ColumnMappings.Add("OrderNum", "OrderNum");

bulkCopy.ColumnMappings.Add("IsCity", "IsCity");

bulkCopy.WriteToServer(table);

}

}

时间缩减到4秒左右，其中主要是在EF查询City表并为每一个Counties赋值时耗时占了大半。但这个的优化我觉得暂时做不到了，先这样吧。