分类:
2009-07-09 09:25:18
一、 几种删除方法代码
1. 查询结果中删除
private void Delete1(IFeatureClass PFeatureclass)
{
IQueryFilter pQueryFilter = new QueryFilterClass();
pQueryFilter.WhereClause = "objectID<=" + DeleteNum;
IFeatureCursor pFeatureCursor = PFeatureclass.Search(pQueryFilter, false); IFeature pFeature = pFeatureCursor.NextFeature();
while (pFeature != null)
{
pFeature.Delete();
pFeature = pFeatureCursor.NextFeature();
}
System.Runtime.InteropServices.Marshal.ReleaseComObject(pQueryFilter);
}
2. 更新游标删除
private void Delete2(IFeatureClass PFeatureclass)
{
IQueryFilter pQueryFilter = new QueryFilterClass();
pQueryFilter.WhereClause = "objectID<=" + DeleteNum;
IFeatureCursor pFeatureCursor = PFeatureclass.Update(pQueryFilter, false);
IFeature pFeature = pFeatureCursor.NextFeature();
while (pFeature != null)
{
pFeatureCursor.DeleteFeature();
pFeature = pFeatureCursor.NextFeature();
}
System.Runtime.InteropServices.Marshal.ReleaseComObject(pQueryFilter);
}
3. 使用DeleteSearchedRows删除
private void Delete4(IFeatureClass PFeatureclass)
{
IQueryFilter pQueryFilter = new QueryFilterClass();
pQueryFilter.WhereClause = "objectID<=" + DeleteNum;
ITable pTable = PFeatureclass as ITable;
pTable.DeleteSearchedRows(pQueryFilter);
System.Runtime.InteropServices.Marshal.ReleaseComObject(pQueryFilter);
}
4. ExecuteSQL删除
private void Delete4(IFeatureClass PFeatureclass)
{
IDataset pDataset = PFeatureclass as IDataset;
pDataset.Workspace.ExecuteSQL("delete from " + PFeatureclass.AliasName + " where objectid<=" + DeleteNum);
}
二、 测试性能和比较
1、 相同的数据条件,删除2000条记录
2、 测试代码
IFeatureLayer pFeatureLayer = axMapControl1.Map.get_Layer(0) as IFeatureLayer;
IFeatureClass PFeatureClass = pFeatureLayer.FeatureClass;
System.Diagnostics.Stopwatch MyWatch = new System.Diagnostics.Stopwatch();
MyWatch.Start();
Delete1(PFeatureClass)
//Delete2(PFeatureClass);
//Delete3(PFeatureClass);
//Delete4(PFeatureClass);
//Delete5(PFeatureClass);
MyWatch.Stop();
MessageBox.Show("删除时间:" + MyWatch.ElapsedMilliseconds.ToString() + "毫秒");
3、 测试情况
测试方法 |
第一次时间(单位ms) |
第一次时间(单位ms) |
1 |
5214ms |
5735ms |
2 |
299ms |
290Ms |
3 |
59ms |
28ms |
4 |
26ms |
26ms |
三、 结论
1、 使用ExecuteSQL删除最快,数据库的效率最高。
2、 DeleteSearchedRows和ExecuteSQL属于批量删除,性能较优。
3、 查询结果中删除,速度最慢,如果你使用这种方法,建立你马上修改你的程序,因为你在浪费时间。