C#对数据库操作注意问题总结
1． 将对数据库连接的open,close，查询，等常用的操作放在一个类中，供其他类公用。
public CGoble()
{
//
// TODO: 在此处添加构造函数逻辑
//sPCName="";//以后要改回来?????????????????????????????
sPCName="M-C6C3J1X";
GetHostName();//获取服务器名
//workstation id="M-C6C3J1X";packet size=4096;integrated security=SSPI;initial catalog=AUTOTEST;persist security info=False
//workstation id="M-C6C3J1X";packet size=4096;integrated security=SSPI;data source="M-C6C3J1X";persist security info=False;initial catalog=AUTOTEST
strConn="workstation id= " + sPCName + " ;packet size=4096;integrated security=SSPI;data source= " + sPCName + " ;persist security info=False; initial catalog=AUTOTEST";
}
public void OpenConn(SqlConnection sqlConn)
{
if(sqlConn.State==ConnectionState.Closed )
sqlConn.Open();
}
public void CloseConn(SqlConnection sqlConn)
{
if(sqlConn.State==ConnectionState.Open )
sqlConn.Close();
}
public DataSet ReturnTable(String strTable ,String strCommand ,bool IfSQL , DataSet sqlDS)
{
SqlCommand myCommand=new SqlCommand();
SqlDataAdapter sqlAdapter;
SqlConnection sqlConn=new SqlConnection();
sqlAdapter=new SqlDataAdapter();
try
{
sqlConn.ConnectionString=strConn;//new SqlConnection(strConn);
//if(sqlConn.State==ConnectionState.Closed )
OpenConn(sqlConn);
myCommand.CommandText =strCommand;
myCommand.Connection=sqlConn;
//myCommand=new SqlCommand(strCommand,sqlConn);
if (IfSQL)
myCommand.CommandType = CommandType.Text;
else
myCommand.CommandType = CommandType.StoredProcedure;
sqlAdapter.TableMappings.Add("Table", strTable);
sqlAdapter.SelectCommand = myCommand;
sqlAdapter.Fill(sqlDS);
}
catch(Exception e)
{
MessageBox.Show(e.ToString(), "错误",MessageBoxButtons.OK, MessageBoxIcon.Error);
}
//if(sqlConn.State==ConnectionState.Open)
CloseConn(sqlConn);
sqlAdapter.Dispose();
myCommand.Dispose();
sqlConn.Dispose();
return sqlDS;
}
其他类在查询时，可直接调用：
strComm="select * from DTestType "; theSet=myGoble.ReturnTable("DTestType",strComm,true,theSet); //TypeNo:测试分类更新、
插入：
SqlConnection theConn=new SqlConnection(myGoble.strConn);
myGoble.OpenConn(theConn);
m_ParamNo=ParamNo.Text.Trim();
strComm="insert into DControlParam values ('"+m_ParamNo+"' ,'"+m_TestTypeNo+"','"+m_ParamName+"',"+m_ParamIndex +","+m_ByteNum+","+m_ParamScale+")";
SqlCommand theComm=new SqlCommand(strComm,theConn);
theComm.CommandType =CommandType.Text ;
try
{
theComm.ExecuteNonQuery();
MessageBox.Show("添加成功!!", "信息",MessageBoxButtons.OK, MessageBoxIcon.Information );
theParamNo=ParamNo.Text.Trim();
}
catch(Exception ex)
{
MessageBox.Show(ex.ToString(), "错误",MessageBoxButtons.OK, MessageBoxIcon.Error);
theParamNo="";
}
myGoble.CloseConn(theConn);
theConn.Dispose();
theComm.Dispose();
修改：
string strComm;
if(!CheckInput())
return;
SqlConnection theConn=new SqlConnection(goble.strConn);
goble.OpenConn(theConn);
strComm="update In_OutputInfo set GroupNo='"+mGroupNo+"',StepNo='"+ mStepNo+"', SubStepNo="+ mSubNo +
",IONo='"+ mIONo +"',IOPriority="+ priority +",FrameNo='"+ mFrameNo +"',ByteIndex='"+ mByteIndex +
"',ByteNum='"+ mByteNum +"',IOFlag='"+ mIOFlag +"',DelayTime="+ delayTime +",MaskValue='"+ mMaskValue +
"',ExpectValue='"+ mExpectValue +"'where GroupNo='"+ m_GroupNo +"' and StepNo='"+ m_StepNo +"' and SubStepNo="+ m_SubNo ;
SqlCommand theComm=new SqlCommand(strComm,theConn);
theComm.CommandType =CommandType.Text ;
try
{
theComm.ExecuteNonQuery();
MessageBox.Show("修改成功!!", "信息",MessageBoxButtons.OK, MessageBoxIcon.Information );
}
catch(Exception ex)
{
MessageBox.Show(ex.ToString(), "错误",MessageBoxButtons.OK, MessageBoxIcon.Error);
}
goble.CloseConn(theConn);
theConn.Dispose();
theComm.Dispose();
删除操作：
string strComm;
SqlConnection theConn=new SqlConnection(goble.strConn);
goble.OpenConn(theConn);
strComm="delete In_OutputInfo where GroupNo='"+ m_GroupNo +"' and StepNo='"+ m_StepNo +"' and SubStepNo="+ m_SubNo ;
SqlCommand theComm=new SqlCommand(strComm,theConn);
theComm.CommandType =CommandType.Text ;
try
{
theComm.ExecuteNonQuery();
MessageBox.Show("删除成功!!", "信息",MessageBoxButtons.OK, MessageBoxIcon.Information );
}
catch(Exception ex)
{
MessageBox.Show(ex.ToString(), "错误",MessageBoxButtons.OK, MessageBoxIcon.Error);
}
goble.CloseConn(theConn);
theConn.Dispose();
theComm.Dispose();
ClearTextBox();
strComm="select * from view_io where StepNo='"+ m_StepNo +"' and GroupNo='"+ m_GroupNo +"' order by GroupNo";
ReturnIOInfo(strComm);
button3.Enabled=false;
button4.Enabled=false;
在DataGrid中显示数据：
try
{
theSet.Tables["IOInfo"].Clear();
}
catch
{
;
}
theSet=goble.ReturnTable("IOInfo",strComm,true,theSet);
dataGrid1.DataSource=theSet.Tables["IOInfo"];
DataGridTableStyle ds = new DataGridTableStyle(true);
ds.MappingName ="IOInfo";// myDataTable.TableName;
this.dataGrid1.TableStyles.Clear();
this.dataGrid1.TableStyles.Add(ds);
2． 在每次要通过查询获得更新DataSet时，要先Clear(),否则不能更新。如上所示
3． 两表联合查询：
strComm="select DControlParam.*,ValueDiscrible,ParamValue,ValueID from DControlParam LEFT JOIN ControlValueInfo on ControlValueInfo.ParamNo=DControlParam.ParamNo where DControlParam.ParamNo='"+ParamNo+"' ";