C#代码的数据库打开关闭问题public class DbHelperOleDb{private string connectionString string.Empty
C#代码的数据库打开关闭问题
public class DbHelperOleDb
{
private string connectionString = string.Empty;
public DbHelperOleDb(string conn)
{
connectionString = conn;
}
#region 执行简单SQL语句
/// <summary>
/// 执行SQL语句，返回影响的记录数
/// </summary>
/// <param name="SQLString">SQL语句</param>
/// <returns>影响的记录数</returns>
public int ExecuteSql(string SQLString)
{
using (OleDbConnection connection = new OleDbConnection(connectionString))
{
using (OleDbCommand cmd = new OleDbCommand(SQLString, connection))
{
try
{
connection.Open();
int rows = cmd.ExecuteNonQuery();
return rows;
}
catch (System.Data.OleDb.OleDbException E)
{
connection.Close();
throw new Exception(E.Message);
}
}
}
}
#endregion
}
请问上述的C#代码，使用using方式来打开数据库，虽然可以用完后扔掉资源，我的问题是：ExecuteSql执行完了之后会保证关闭打开的数据库吗？（不出现异常的情况下），谢谢各位大神，本人这两天开始接触C#
------解决方案--------------------
using(var connection = new Connection())
{
connection.Open();
}
相当于
try
{
var connection = new Connection();
connection.Open();
}
finally
{
connection.Close();
}
[解决办法]可以关闭打开的连接.因为Using会调用OleDbConnection的IDispot接口.catch(System.Data.OleDb.OleDbException E)
{
connection.Close();//这是一条无意义的代码
throw new Exception(E.Message);
}
[解决办法]Code Original:
//连接数据库的字符串.
string strConn = ConfigurationManager.ConnectionStrings["ADONetTest.Properties.Settings.DBTestConnectionString"].ConnectionString;
using (SqlConnection conn = new SqlConnection(strConn)) {
conn.Open();
using (SqlCommand cmd = conn.CreateCommand()) {
cmd.CommandText = "Insert into T_Persons(FName) values('King')";
cmd.ExecuteNonQuery();
MessageBox.Show("Done!");
}
}
Reflector Code:
bool flag;
string strConn = ConfigurationManager.ConnectionStrings["ADONetTest.Properties.Settings.DBTestConnectionString"].ConnectionString;
SqlConnection conn = new SqlConnection(strConn);
try {
conn.Open();
SqlCommand cmd = conn.CreateCommand();
try {
cmd.CommandText = "Insert into T_Persons(FName) values('King')";
cmd.ExecuteNonQuery();
MessageBox.Show("Done!");
}
finally {
flag = cmd == null;
if (!flag) {
((IDisposable)cmd).Dispose();
}
}
}
finally {
flag = conn == null;
if (!flag) {
((IDisposable)conn).Dispose();
}
}
这个微软还是会想到了,放心吧...两层的Try catch...
