C# 将数据集转换为整数
看,我有这个密码:C# 将数据集转换为整数,c#,database,dataset,integer,C#,Database,Dataset,Integer,看,我有这个密码: private void obtengoUltimoComienzoColocado() { ManejoUsuarios lAdm = new ManejoUsuarios(); lblTodoOK.Text = lAdm.LevantoUltimoIDBarco().ToString(); } public int LevantoUltimoIDBarco() { Conexion
private void obtengoUltimoComienzoColocado()
{
ManejoUsuarios lAdm = new ManejoUsuarios();
lblTodoOK.Text = lAdm.LevantoUltimoIDBarco().ToString();
}
public int LevantoUltimoIDBarco()
{
ConexionBD lP = new ConexionBD();
try
{
string lQuery = "Select Max(idBarco) as UltimoID From Comienzos;";
Convert.ToInt32(lP.ObtenerRegistro(lQuery));
return 1;
}
catch (Exception ex)
{
return 0;
}
}
public DataSet ObtenerRegistro(string SqlQuery)
{
DataSet lResult;
SqlConnection lSqlConnection = new SqlConnection("Data Source=SEBA-PC\\sqlexpress;Initial Catalog=Batalla_Naval;Integrated Security=True");
SqlCommand lSqlCommand = null;
try
{
lSqlCommand = new SqlCommand();
lSqlCommand.CommandText = SqlQuery;
lSqlCommand.CommandType = CommandType.Text;
SqlDataAdapter lAdapter = new SqlDataAdapter(lSqlCommand);
lResult = new DataSet();
lSqlConnection.Open();
lSqlCommand.Connection = lSqlConnection;
lAdapter.Fill(lResult);
}
catch (Exception)
{
throw;
}
finally
{
lSqlConnection.Close();
}
return lResult;
}
如您所见,我使用三个函数访问数据库并从Comienzos表中获取最大ID,但当我想将数据集转换为int32时,函数LevantoUltimoIDBarco返回我0,查看如何检索数据,然后读取该整数(max())的正确代码如下
string lQuery = "Select Max(idBarco) as UltimoID From Comienzos;";
DataSet ds = lP.ObtenerRegistro(lQuery);
return Convert.ToInt32(ds.Tables[0].Rows[0][0] == DBNull.Value ? 0 : ds.Tables[0].Rows[0][0]);
但是,如果您的表没有记录,则MAX(idBarco)将返回DBNull作为结果您必须从数据集中选择第一个值,您无法将完整的数据集转换为整数:
Convert.ToInt32(lP.ObtenerRegistro(lQuery).Tables[0].Rows[0][0]);
或者更简单(因为查询在数据集中返回一个整数):
然后您必须返回或保存结果,而不是只返回1。我的朋友,您应该使用
ExecuteScalar
返回单个值,而不是适配器并填充数据集
SqlConnection lSqlConnection = new SqlConnection("Data Source=SEBA-PC\\sqlexpress;Initial Catalog=Batalla_Naval;Integrated Security=True");
SqlCommand lSqlCommand = null;
try
{
lSqlCommand = new SqlCommand();
lSqlCommand.CommandText = SqlQuery;
lSqlCommand.CommandType = CommandType.Text;
var result = lSqlCommand.ExecuteScalar();
int MyID = Convert.ToInt32(result);
}
catch(ex)
{
// DO SOMETHING
}
您使用此代码的地方:
Convert.ToInt32(lP.ObtenerRegistro(lQuery))代码>非常有用,我成功了!谢谢
SqlConnection lSqlConnection = new SqlConnection("Data Source=SEBA-PC\\sqlexpress;Initial Catalog=Batalla_Naval;Integrated Security=True");
SqlCommand lSqlCommand = null;
try
{
lSqlCommand = new SqlCommand();
lSqlCommand.CommandText = SqlQuery;
lSqlCommand.CommandType = CommandType.Text;
var result = lSqlCommand.ExecuteScalar();
int MyID = Convert.ToInt32(result);
}
catch(ex)
{
// DO SOMETHING
}