出现并非所有路径代码都有返回值是怎么回事呀，求助！

[yanlan112]

编写了一个DBHELPER类，内容为：
using System;
using System.Collections.Generic;
using System.Text;
using System.Data.SqlClient;
using System.Configuration;
using System.Web.Configuration;
using System.Data;

namespace DBHelp
{
public class DBHelper
{
private static SqlConnection conn;
/// <summary>
/// 数据库连接
/// </summary>
/// <returns></returns>
public static SqlConnection Conn
{

get
{
if(conn==null)
{
conn=new SqlConnection(ConfigurationManager.ConnectionStrings["book"].ConnectionString.ToString());
conn.Open();
}
else if(conn.State==System.Data.ConnectionState.Closed)
{
conn.Open();
}
else if(conn.State==System.Data.ConnectionState.Broken)
{
conn.Close();
conn.Open();
}
return conn;
}
}
/// <summary>
/// 生成SQL参数
/// </summary>
/// <param name="newname"></param>
/// <param name="dbtype"></param>
/// <param name="value"></param>
/// <returns></returns>
public static SqlParameter GetParam(string newname, SqlDbType dbtype, object value)
{
SqlParameter aaa = new SqlParameter(newname, dbtype);
aaa.Value = value;
return aaa;
}
/// <summary>
/// 返回COMMAND
/// </summary>
/// <param name="sql"></param>
/// <returns></returns>
public static SqlCommand Getcmd(string sql,SqlParameter[] value)
{
SqlCommand cmd = new SqlCommand(sql, Conn);
if(value==null)
{
return cmd;
}
else
{
cmd.Parameters.AddRange(value);
return cmd;
}
}
/// <summary>
/// 返回错误信息
/// </summary>
/// <param name="err"></param>
/// <returns></returns>
public static string err()
{
return _err;
}
public static string _err;
/// <summary>
/// 执行SQL语句,返回受影响的行数
/// </summary>
/// <param name="cmd"></param>
/// <param name="value"></param>
/// <returns></returns>
public static int Execute(SqlCommand cmd)
{
try
{
int a=cmd.ExecuteNonQuery();
return a;
}
catch (Exception e)
{
_err = e.Message.ToString();
}
finally
{
Conn.Close();
}
}
/// <summary>
/// 返回DataReader
/// </summary>
/// <param name="cmd"></param>
/// <returns></returns>
public static SqlDataReader GetReader(SqlCommand cmd)
{
try
{
SqlDataReader sdr = cmd.ExecuteReader(CommandBehavior.CloseConnection);
return sdr;
}
catch (Exception e)
{
_err = e.Message.ToString();
}
finally
{
Conn.Close();
}
}
/// <summary>
/// 根据CMD返回数据表DataTable
/// </summary>
/// <param name="cmd"></param>
/// <returns></returns>
public static DataTable GetDataTable(SqlCommand cmd)
{
try
{
SqlDataAdapter sda = new SqlDataAdapter(cmd);
DataSet ds = new DataSet();
sda.Fill(ds, "t1");
return ds.Tables["t1"];
}
catch (Exception e)
{
_err = e.Message.ToString();
}
finally
{
Conn.Close();
}
}





}
}
调试时出现EXECUTE(),GETREADER(),GETDATATABLE()这三个方法出现错误，并非所有代码路径都有返回值，是怎么回事呀
想了半天，弄了半天实在弄不出来了

先谢谢各位了！

[wuyq11]

public static int Execute(SqlCommand cmd)
{
try
{
int a=cmd.ExecuteNonQuery();
return a;
}
catch (Exception e)
{
_err = e.Message.ToString();
}
finally
{
Conn.Close();
}return 0;
}
public static DataTable GetDataTable(SqlCommand cmd)
{
try
{
SqlDataAdapter sda = new SqlDataAdapter(cmd);
DataSet ds = new DataSet();
sda.Fill(ds, "t1");
return ds.Tables["t1"];
}
catch (Exception e)
{
_err = e.Message.ToString();
}
finally
{
Conn.Close();
}
return null;
}

[周公]

public static int Execute(SqlCommand cmd) 
        { 
int a=0;
            try 
            { 
              a=cmd.ExecuteNonQuery(); 
                return a; 
            } 
            catch (Exception e) 
            { 
                _err = e.Message.ToString(); 
            } 
            finally 
            { 
                Conn.Close(); 
            } 
            return a;
        }

[止戈而立]

        public static int Execute(SqlCommand cmd) 
        { 
            int a=0;//加上这句
            try 
            { 
              a=cmd.ExecuteNonQuery(); 
                //return a; 这句不要
            } 
            catch (Exception e) 
            { 
                _err = e.Message.ToString(); 
            } 
            finally 
            { 
                Conn.Close(); 
            } 
            return a;//加上这句
        }

其他两个位置也类似。。只是返回的初始值不同，应置为null

[止戈而立]

        public static SqlDataReader GetReader(SqlCommand cmd) 
        { 
            SqlDataReader sdr=null;
            try 
            { 
                sdr = cmd.ExecuteReader(CommandBehavior.CloseConnection); 
                //return sdr; //注释掉。。
            } 
            catch (Exception e) 
            { 
                _err = e.Message.ToString();
                return null; //加上这句
            } 
            finally 
            { 
                Conn.Close(); 
            }
            return sdr; //放到这里 
        } 

另一个就不用说了。。

[yanlan112]

我是刚开始学做三层，能给这个类一点意见吗？
谢谢

[庚武讲堂]

看得出你的程序修为，实在不想打击你啊，...
一个花括号一个return。
这样基础的问题，不应该问，建议楼主去学学基础，锻炼一下。

[fj_shaodw]

少一个return.都不用看代码就知道。

[mengxj85]

[Quote=引用 7 楼 fjleague 的回复:]
少一个return.都不用看代码就知道。
[/Quote]
.