Sistema de cadastro

Verifique se existem dados em $nome e $senha.
Talvez eles não estão chegando.
Caso estejam preenchidos, tente concatenar as variáveis:
“SELECT * FROM usuarios WHERE nome = '” . $nome . “’ “
“INSERT INTO usuarios(nome, senha) VALUES (’” . $nome .”’, '” . $senha ."’)"

Tem como me passar o código completo ? Está dando este erro:

Warning: mysql_query(): It is not safe to rely on the system’s timezone settings. You are required to use the date.timezone setting or the date_default_timezone_set() function. In case you used any of those methods and you are still getting this warning, you most likely misspelled the timezone identifier. We selected ‘America/Sao_Paulo’ for ‘-3.0/no DST’ instead in C:\WebServer\Apache2.2\htdocs\c\cadastrando.php on line 7 Warning: mysql_query(): Access denied for user ‘’@‘localhost’ (using password: NO) in C:\WebServer\Apache2.2\htdocs\c\cadastrando.php on line 7 Warning: mysql_query(): It is not safe to rely on the system’s timezone settings. You are required to use the date.timezone setting or the date_default_timezone_set() function. In case you used any of those methods and you are still getting this warning, you most likely misspelled the timezone identifier. We selected ‘America/Sao_Paulo’ for ‘-3.0/no DST’ instead in C:\WebServer\Apache2.2\htdocs\c\cadastrando.php on line 7 Warning: mysql_query(): A link to the server could not be established in C:\WebServer\Apache2.2\htdocs\c\cadastrando.php on line 7 Warning: mysql_num_rows(): It is not safe to rely on the system’s timezone settings. You are required to use the date.timezone setting or the date_default_timezone_set() function. In case you used any of those methods and you are still getting this warning, you most likely misspelled the timezone identifier. We selected ‘America/Sao_Paulo’ for ‘-3.0/no DST’ instead in C:\WebServer\Apache2.2\htdocs\c\cadastrando.php on line 8 Warning: mysql_num_rows() expects parameter 1 to be resource, boolean given in C:\WebServer\Apache2.2\htdocs\c\cadastrando.php on line 8 Warning: mysql_query(): It is not safe to rely on the system’s timezone settings. You are required to use the date.timezone setting or the date_default_timezone_set() function. In case you used any of those methods and you are still getting this warning, you most likely misspelled the timezone identifier. We selected ‘America/Sao_Paulo’ for ‘-3.0/no DST’ instead in C:\WebServer\Apache2.2\htdocs\c\cadastrando.php on line 11 Warning: mysql_query(): Access denied for user ‘’@‘localhost’ (using password: NO) in C:\WebServer\Apache2.2\htdocs\c\cadastrando.php on line 11 Warning: mysql_query(): It is not safe to rely on the system’s timezone settings. You are required to use the date.timezone setting or the date_default_timezone_set() function. In case you used any of those methods and you are still getting this warning, you most likely misspelled the timezone identifier. We selected ‘America/Sao_Paulo’ for ‘-3.0/no DST’ instead in C:\WebServer\Apache2.2\htdocs\c\cadastrando.php on line 11 Warning: mysql_query(): A link to the server could not be established in C:\WebServer\Apache2.2\htdocs\c\cadastrando.php on line 11

Cara, tem como passar o arquivo conexao.php?
Talvez tenha algum parâmetro errado ao tentar fazer a conexão.

Boa tarde,
Cara acho que é algo na conexão.

$sql="select * from tabela;

$executeQuery=mysqli_query( $conexaoDoIncludeComOBanco, $sql);

$numberRows=$executeQuery->num_rows;

if($numberRows>0)
         {
          echo "já existe ";   
         }
         else
         {
                       echo "faz outra coisa" ;
             }

se puder colocar o arquivo conexao ajuda. vlw.

Bom, interpretando sua mensagem de erro, alguns pontos:

1. Você precisa definir o timezone usando a função date_default_timezone_set para America/Sao_Paulo…

2. Seu usuário @localhost não têm permissão de acessar a base, artigo a respeito aqui

Tente corrigir esses pontos inicialmente, após vai postando outras mensagens que ocorrer…

Outra coisa, se estiver usando versões mais novas do php, evite usar api mysql_*, dê preferência por PDO ou Mysqli assim você já fica compatível com a versão 7 (que removeu a api antiga) evitando incompatibilidade e o principal, acrescentando mais performance e segurança no seu código…