我试图找出如何使用C#在SQL Server中提高临时表的插入性能。有些人说我应该使用SQLBulkCopy,但似乎它比简单构建SQL插入字符串要慢得多。下面是我使用SQLBulkCopy创建表的代码:
public void MakeTable(string tableName, List<string> ids, SqlConnection connection)
{
SqlCommand cmd = new SqlCommand("CREATE TABLE ##" + tableName + " (ID int)", connection);
cmd.ExecuteNonQuery();
DataTable localTempTable = new DataTable(tableName);
DataColumn id = new DataColumn();
id.DataType = System.Type.GetType("System.Int32");
id.ColumnName = "ID";
localTempTable.Columns.Add(id);
foreach (var item in ids)
{
DataRow row = localTempTable.NewRow();
row[0] = item;
localTempTable.Rows.Add(row);
localTempTable.AcceptChanges();
}
using (SqlBulkCopy bulkCopy = new SqlBulkCopy(connection))
{
bulkCopy.DestinationTableName = "##" + tableName;
bulkCopy.WriteToServer(localTempTable);
}
}
这样我的插入操作需要很长时间才能执行完。我用另一种方法来使我的插入操作更快:
我将插入操作的代码作为字符串创建,并在SQL临时表创建语句中连接它:
创建插入操作字符串:
public string prepareInserts(string tableName, List<string> ids)
{
List<string> inserts = new List<string>();
var total = ids.Select(p => p).Count();
var size = 1000;
var insert = 1;
var skip = size * (insert - 1);
var canPage = skip < total;
while (canPage)
{
inserts.Add(" insert into ##" + tableName + @" (ID) values " + String.Join(",", ids.Select(p => string.Format("({0})", p))
.Skip(skip)
.Take(size)
.ToArray()));
insert++;
skip = size * (insert - 1);
canPage = skip < total;
}
string joinedInserts = String.Join("\r\n", inserts.ToArray());
return joinedInserts;
}
在创建查询后,在SQL语句中使用它们:
inserts = prepareInserts(tableName, ids);
var query = @"IF EXISTS
(
SELECT *
FROM tempdb.dbo.sysobjects
WHERE ID = OBJECT_ID(N'tempdb..##" + tableName + @"')
)
BEGIN
DELETE FROM ##" + tableName + @"
END
ELSE
BEGIN
CREATE TABLE ##" + tableName + @"
(ID int)
END " + inserts;
var command = new SqlCommand(query, sqlConnection);
...
自从我看到有人在stack exchange(https://dba.stackexchange.com/questions/44217/fastest-way-to-insert-30-thousand-rows-in-sql-server/44222?noredirect=1#comment78137_44222)告诉我应该使用SQLBulkCopy,这样会更快,我相信我应该改善我的做法。所以如果有人能建议我如何改进我的SQLBulkCopy代码或告诉我是否有更好的插入语句可以提高我的应用程序性能,那将是非常棒的。