❔ CRUD in Postgresql
I'm trying to select data to my database and put them in a combobox, but i can't get this information.
I can only register informations on the database, but how could i get them?
7 Replies
the registration class:
using Npgsql;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Security.Cryptography.X509Certificates;
using System.Text;
using System.Threading.Tasks;
namespace Orlagenda.Conexoes
{
public class CadastroCliente
{
Conexao conn = new Conexao();
NpgsqlCommand cmd = new NpgsqlCommand();
public String mensagem = "";
public CadastroCliente(string nome, string cpf, string datanasc, string endereco, string cidade, string genero)
{
cmd.CommandText = $"INSERT INTO tb_clientes(nome_cliente, cpf_cliente, datanasc_cliente, endereco_cliente, cidade_cliente, genero_cliente) values(@nome,@cpf,@datanasc,@endereco,@cidade,@genero )";
cmd.Parameters.AddWithValue("@nome",nome);
cmd.Parameters.AddWithValue("@cpf", cpf);
cmd.Parameters.AddWithValue("@datanasc", datanasc);
cmd.Parameters.AddWithValue("@endereco", endereco);
cmd.Parameters.AddWithValue("@cidade", cidade);
cmd.Parameters.AddWithValue("@genero", genero);
try
{
cmd.Connection = conn.estabelecerConexao();
cmd.ExecuteNonQuery();
this.mensagem = "Cadastrado com Sucesso";
}
catch (NpgsqlException e )
{
this.mensagem = "Erro na conexão do Banco" + " " + e;
}
}
}
}
the selection class: using Npgsql;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Runtime.CompilerServices;
using System.Security.Cryptography.X509Certificates;
using System.Text;
using System.Threading.Tasks;
namespace Orlagenda.Conexoes
{
public class Clientes
{
NpgsqlCommand cmd = new NpgsqlCommand();
public Clientes(string nome)
{
Conexao conn = new Conexao();
NpgsqlCommand cmd = new NpgsqlCommand();
cmd.CommandText = $"SELECT nome_cliente from tb_clientes;";
cmd.Parameters.AddWithValue("nome_cliente", nome);
try
{
cmd.Connection = conn.estabelecerConexao();
cmd.ExecuteNonQuery();
}
catch (NpgsqlException e )
{
} } } }
} } } }
Why don't you use EntityFramework. I think it's compatible with PostgreSql
i found a video about it but i kind of dont know how to use it
and the first part was already done, so i didn't knew if it was confuse my code
Take a look here https://sqlines.com/postgresql/npgsql_cs_result_sets
I don't know exactly but before I used Entity Framework for INSERT I'd use cmd.ExecuteNonQuery(); Like you have.
But to SELECT it was another command
cmd.CommandText = $"SELECT nome_cliente from tb_clientes;";
cmd.Parameters.AddWithValue("nome_cliente", nome);
You have only this but I don't see where you are storing the values retreived from SELECT
Maybe I am not reading well your code.
Mas use a Entity Framework é melhor. E tem muito tutorial 🙂
thx bro, im already seeing a Entity Framework video, but i'll check this site for sure
ExecuteNonQuery doesnt return a response, it's not for queries
Since you are only selecting a single column, you could use
ExecuteScalar
Otherwise you would use ExecuteDataReaderWas this issue resolved? If so, run
/close - otherwise I will mark this as stale and this post will be archived until there is new activity.