使用GROUP BY，ORDER BY进行PDO查询构造

I am having trouble using GROUP BY, ORDER BY , LIMIT, in general my queries work fine however when I try to get more specific I keep running into problems. I try to break it down and go step by step but I can't figure out issue.

我在使用GROUP BY,ORDER BY,LIMIT时遇到问题,一般情况下我的查询工作正常,但是当我尝试更具体时,我会遇到问题。我试图将其分解并逐步进行,但我无法弄清楚问题。

From my User Class I call DB like this:

从我的用户类我这样称为DB:

$this->_db->get('listings', array('userid', '=', $this->data()->id, ' AND ',
'email', ' = ', $this->data()->email, ' GROUP BY reference ORDER BY row ASC'));

My DB Class is set up like this:

我的DB类设置如下:

public function get($table, $where){return $this->action('SELECT * ', $table, $where);}


private function action($action, $table, $where = array()){
        $operators = array('=', '>', '<', '>=', '<=' , 'AND' ,'OR', 'LIKE', 'GROUP BY','ORDER BY', 'ASC', 'DESC');

        if(!empty($where)){
            $sql = "{$action} FROM {$table} WHERE ";
            if(count($where) > 3){
                $sql .= "(";
                $isOp = FALSE;
                foreach ($where as $key => $value) {
                    if($isOp){ 
                        if(in_array($value, $operators)){
                            $sql .= " {$value} ";
                            $isOp = FALSE;
                        }else{return FALSE;}
                    }else{
                        $sql .= " {$value} ";
                        $isOp = TRUE;
                    }
                }
                $sql .= ")";

                if(!$this->query($sql, array($value))->error()){return $this;}
            }else if(count($where) === 3){
                $field      = $where[0]; 
                $operator   = $where[1];
                $value      = $where[2];
                if(in_array($operator, $operators)){
                    $sql = "{$action} FROM {$table} WHERE {$field} {$operator} ?"; // NO $value ?
                    if(!$this->query($sql, array($value))->error()){return $this;}
                }
            }
        }else{
            // If array is empty
            $sql = "{$action} FROM {$table}";
            if(!$this->query($sql)->error()){return $this;}
        }
        return FALSE;
    }


public function query($sql, $params = array()){
        $this->_error = FALSE;
        if($this->_query = $this->_pdo->prepare($sql)){
            $x = 1;
            if(count($params)){
                foreach($params as $param){
                    $this->_query->bindValue($x, $param);
                    $x++;
                }
            }// End IF count

            if($this->_query->execute()){
                    $this->_lastID = $this->_pdo->lastInsertId();
                    try{
                        $this->_results = $this->_query->fetchAll(PDO::FETCH_OBJ);
                    }catch(Exception $e){
                        // Catch Error
                    }
                    $this->_count = $this->_query->rowCount();
            }else{$this->_error = TRUE;}
        }
        return $this;
    }

In general I am building everything from scratch by reading tutorials and following instructions from books.

一般来说,我通过阅读教程和遵循书中的说明从头开始构建所有内容。

Again I am having trouble with the following Group By, Order By, Like, Limit.. I am probably not binding it correctly however I don't have enough knowledge to find my mistake.

我再次遇到以下Group By,Order By,Like,Limit ..我可能没有正确绑定它但是我没有足够的知识来找到我的错误。

Thanks in advance.

提前致谢。

ERROR I GET

我得到的错误

SELECT * FROM listings WHERE ( userid = 4 GROUP BY reference )exception 'PDOException' with message 'SQLSTATE[42000]: Syntax error or access violation: 1064 You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'GROUP BY reference )' at line 1

SELECT * FROM listing WHERE(userid = 4 GROUP BY reference)异常'PDOException',消息'SQLSTATE [42000]:语法错误或访问冲突:1064 SQL语法中有错误;检查与您的MySQL服务器版本对应的手册,以便在第1行的“GROUP BY参考”附近使用正确的语法

1 个解决方案

#1

I would get rid of de ( ) in you code (DB class):

我会在你的代码(DB类)中删除de():

$sql .= "(";
$sql .= ")";

The GROUP BY should not be in the () section of the WHERE.

GROUP BY不应该在WHERE的()部分。

WHERE ( userid = 4 GROUP BY reference )

WHERE(userid = 4 GROUP BY引用)

Must be:

WHERE ( userid = 4 ) GROUP BY reference;

Or better:

WHERE userid = 4 GROUP BY reference;

You use the GROUP BY function when you use SUM, COUNT, etc. in the SELECT. Else you don't need it.

在SELECT中使用SUM,COUNT等时,可以使用GROUP BY函数。否则你不需要它。

1 个解决方案

#1

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