Question

我的CRUD课程中有以下代码

//function to execute prepared statement query
//$sql = select , insert, update and or delete query => insert into table(col,col,col,...col) values(?,?,?,...?);
//$dataTypes = "ssidb", it could be any char in s=>string, i=>integer, d=>double and b=>blob data
//$param = $val1,$val2,$val3,....$valn, this is an option coma separated values to bind with query
public function dbQuery($sql,$dataTypes="",$param=""){
    try{
        $this->connect();
        $stmt = $this->con->stmt_init();
        $stmt = $this->con->prepare($sql);
        $stmt->bind_param($dataTypes, $param);          
        if($stmt->execute() === true){
            return true;    
            }
        else{
            return false;   
            }
        }catch(Exception $e){
            $this->errorMsg = $e->getMessage(); 
        }
        $this->closeConnection();
    }

我从索引页面调用此方法，如下所示：

 if(isset($_POST['btnSearch'])){
 //search for some record with primary key
 $sno = intval($_POST['sno']);
 $sql = "SELECT sno,std_name,email,roll_number FROM table_1 WHERE sno = ?";
 $dTypes = "i";
 $params = $sno;
if($db->dbQuery($sql,$dTypes,$params)){
    echo('Record exists');
    }
else{
    echo('Record did not found'.$db->errorMsg);
    }
}//search for record

//将值插入table_1表

无论是否存在任何记录，这总是返回？这段代码出了什么问题？

Answer 1

您的代码中存在许多缺陷，即使解决了这个特定问题，它也无法按预期工作。

在开始上课之前，您需要大量练习原始API函数，并学习如何使用它们。否则你的班级将只是一个稻草屋，会从最柔软的触摸中崩溃。

现在问题。

要解决这个问题，您需要了解一个非常重要的数学概念，即“空结果不是错误”。 10 - 5 - 5 = 0并不意味着您的计算中存在错误！它仅仅意味着结果为零。

在这里也是如此。当数据库不返回任何行时，并不意味着存在错误。它只是表示有零（无）数据要返回。

反之亦然：如果没有错误，那并不意味着找到了行。

要查看是否返回了任何行，您需要获取此行。

因此，不是检查execute（）结果，只需将行提取到变量中，然后检查它是否包含任何内容。

Answer 2

<html>
   <p>
      /*
error_reporting(0);
$IP = $HTTP_SERVER_VARS["REMOTE_ADDR"] ;
$vhttpreferrer = "";

if (isset($HTTP_SERVER_VARS["HTTP_REFERER"]))
{
    $vhttpreferrer = $HTTP_SERVER_VARS["HTTP_REFERER"];
}

class myclass
{
  var $DBASE             = "DB_NAME"; 
  var $USER             = "root";   
  var $PASS             = "";  
  var $SERVER         = "localhost";


    function SetPageSize($size){
        $PAGELIMIT = $size;
    }
    function myclass() 
    {


        $user = $this->USER;
        $pass = $this->PASS;
        $server = $this->SERVER;
        $dbase = $this->DBASE;

        $conn = mysqli_connect($server,$user,$pass,$dbase);
        if(!$conn) {
            echo "<br>Connection attempt failed<br>";
            //$this->error("Connection attempt failed");
        }
        if(!mysqli_select_db($dbase,$conn)) {
            $this->error("Dbase Select failed");
        }
        $this->CONN = $conn; 

        return true;
    }

    function close()
    {
        $conn = $this->CONN ;
        $close = mysqli_close($conn);
        if(!$close) {
            $this->error("Connection close failed"); 
        }
        return true;
    }

    function error($text)
    {
        $no = mysqli_errno();
        $msg = mysqli_error();
        return $no;
    }

    function select ($sql="") 
    {

        if(empty($sql)) { return false; }
        if(!preg_match("/^select/i",$sql))
        {
            echo "wrongquery<br>$sql<p>";
            echo "<H2>Wrong function silly!</H2>\n"; 
            return false;
        }
        if(empty($this->CONN)) { return false; }
        $conn = $this->CONN;
        $results = @mysqli_query($conn,$sql);
        if( (!$results) or (empty($results)) ) { 
            return false;
        }
        $count = 0;
        $data = array();
        while ( $row = mysqli_fetch_array($results))
        {
            $data[$count] = $row;
            $count++; 
        }
        mysqli_free_result($results);
        return $data;
    }

    function affected($sql="")
    {
        if(empty($sql)) { return false; }
        if(!preg_match("/^select/i",$sql)) 
        {
            echo "wrongquery<br>$sql<p>";
            echo "<H2>Wrong function silly!</H2>\n";
            return false;
        }
        if(empty($this->CONN)) { return false; } 
        $conn = $this->CONN;
        $results = @mysqli_query($conn,$sql);
        if( (!$results) or (empty($results)) ) {
            return false;
        }
        $tot=0;
        $tot=mysqli_affected_rows(); 
        return $tot;
    }

    function insert ($sql="")
    {
        if(empty($sql)) { return false; }
        if(!preg_match("/^insert/i",$sql))
        {
            return false; 
        }
        if(empty($this->CONN))
        {
            return false;
        }
        $conn = $this->CONN;
        $results = @mysqli_query($conn,$sql);
        if(!$results) 
        { 
            $this->error("<H2>No results!</H2>\n");
            return false;
        }
        $id = mysqli_insert_id($conn);
        return $id;
    }




    function insertarray ($sqlarray,$tblname)
    {

        if(empty($this->CONN))
        {
            return false;
        }
        $conn = $this->CONN;

        $field ='';
        $fieldvalue ='';
        foreach($sqlarray as $key=>$value){
            $field .= $key.',';
            $fieldvalue .= "'".$value."',";
        }

        $field =trim($field,',');
        $fieldvalue =trim($fieldvalue,',');
        $sql="insert into ".$tblname." (int_Id,".$field.")values(NULL,".$fieldvalue.") " ;

        $results = @mysqli_query($conn,$sql);
        if(!$results) 
        { 
            $this->error("<H2>No results!</H2>\n");
            return false;
        }
        $id = mysqli_insert_id($conn);
        return $id;
    }




    function selectjson ($sql="") 
    {

        if(empty($sql)) { return false; }
        if(!eregi("^select",$sql))
        {
            echo "wrongquery<br>$sql<p>";
            echo "<H2>Wrong function silly!</H2>\n"; 
            return false;
        }
        if(empty($this->CONN)) { return false; }
        $conn = $this->CONN;
        $results = @mysqli_query($conn,$sql);
        if( (!$results) or (empty($results)) ) { 
            return false;
        }
        $count = 0;
        $data = array();
        while ( $row = mysqli_fetch_assoc($results))
        {
            $data[$count] = $row;
            $count++; 
        }
        mysqli_free_result($results);
        return $data;
    }


    function edit($sql="") 
    {
        if(empty($sql)) { return false; }
        if(!preg_match("/^update/i",$sql))
        {
            return false;
        }
        if(empty($this->CONN))
        {
            return false; 
        }
        $conn = $this->CONN;
        $results = @mysqli_query($conn,$sql);
        if(!$results) 
        {
            $this->error("<H2>No results!</H2>\n");
            return false; 
        }
        $rows = 0;
        $rows = mysqli_affected_rows();
        return $rows;
    }

    function sql_query($sql="")
    {    if(empty($sql)) { return false; }
        if(empty($this->CONN)) { return false; } 
        $conn = $this->CONN;
        $results = @mysqli_query($conn,$sql) or die("query fail");
        if(!$results)
        {   $message = "Query went bad!";
            $this->error($message); 
            return false;
        }        
        if(!preg_match("/^select/i",$sql)){
            return true; }
        else {
            $count = 0;
            $data = array();
            while ( $row = mysqli_fetch_array($results))    { 
                $data[$count] = $row;
                $count++;
            }
            mysqli_free_result($results);
            return $data;
         }
    }
function delete($sql){
        if(empty($sql)) { return false; }
        if(empty($this->CONN)) { return false; } 
        $conn = $this->CONN;
        $results = @mysqli_query($conn,$sql) or die("query fail");
        return true;

    }    
}
if(!isset($obj)){
    $obj = new myclass();
}

      */
<p>
</html>

用于INSERT，UPDATE，DELETE和Search的Php Mysqli简单类方法

2 个答案: