/**

* SQL 简单查询工具类

*

* $tools = new SQLTools("表名", "数据库操作对象实例");

*$tools->query("字段默认为*") //(如无后续操作此处返回查询结果集)

* ->where( '条件', PDO参数化查询参数 ) //(如无后续操作此处返回查询结果集)

* ->group( 'id' ) //(如无后续操作此处返回查询结果集)

* ->order( 'id', 'desc' ) //(如无后续操作此处返回查询结果集)

* ->limit( 0, 100 ) //(如无后续操作此处返回查询结果集)

* ->toSQL(); // 返回拼接出来的SQL

*

*

*/

defined( 'SQL_TAG_QUERY' ) OR define( 'SQL_TAG_QUERY', 'query' );

defined( 'SQL_TAG_LIMIG' ) OR define( 'SQL_TAG_LIMIT', 'limit' );

defined( 'SQL_TAG_WHERE' ) OR define( 'SQL_TAG_WHERE', 'where' );

defined( 'SQL_TAG_ORDER' ) OR define( 'SQL_TAG_ORDER', 'order' );

defined( 'SQL_TAG_GROUP' ) OR define( 'SQL_TAG_GROUP', 'group' );

// to xx 自己加吧

defined( 'TO_SQL' ) OR define( 'TO_SQL', 'toSQL' );

class SQLTools{

public $id = null;

public $db = null;

public $tableName = null;

private $__code = null;

private $__query = null;

private $__where = null;

private $__param = null;

private $__limit = null;

private $__order = null;

private $__group = null;

/**

* 实例化

* @param $tableName stirng 表名

* @param $db 一个数据库操作对象，且必须有个叫query的方法，接受两个参数 sql 及 params

* @param $id 主键字段名

*/

public function __construct( $tableName, $db, $id=null ){

$this->db = $db;

$this->id = $id;

$this->tableName = $tableName;

}

public function query( $fields='*', $tableName=null ){

$tableName === null && ( $tableName = $this->tableName );

$this->__query = "SELECT $fields FROM $tableName ";

return $this->__setResultByCallCode( SQL_TAG_QUERY );

}

public function where( $where, $params ){

$this->__where = "WHERE $where ";

$this->__param = $params;

return $this->__setResultByCallCode( SQL_TAG_WHERE );

}

public function order( $fields, $sort ){

$this->__order = "ORDER BY $fields $sort ";

return $this->__setResultByCallCode( SQL_TAG_ORDER );

}

public function group( $fields ){

$this->__group = "GROUP BY $fields";

return $this->__setResultByCallCode( SQL_TAG_GROUP );

}

public function limit( $m, $n ){

$this->__limit = sprintf( 'LIMIT %d,%s ', $m, $n );

return $this->__setResultByCallCode( SQL_TAG_LIMIT );

}

public function toSQL(){ return $this->__setResultByCallCode( TO_SQL ); }

public function clear(){

$this->__code = null;

$this->__query = null;

$this->__where = null;

$this->__param = null;

$this->__limit = null;

$this->__order = null;

$this->__group = null;

}

// 真正查询的地方

private function __query( $tag ){

$__sql = $this->__query;

$this->__where !== null && ( $__sql .= $this->__where );

$this->__group !== null && ( $__sql .= $this->__group );

$this->__order !== null && ( $__sql .= $this->__order );

$this->__limit !== null && ( $__sql .= $this->__limit );

$result = $tag === TO_SQL ? $__sql : $this->db->query( $__sql, $this->__param );

$this->clear();

return $result;

}

/**

* 通过堆栈信息获取调用脚本后面调用方法，

* 根据方法生成相关返回对象

* @param $tag sql标签

* @return object

**/

private function __setResultByCallCode( $tag ){

if( $this->__code !== null ){

return $this->__createResult( $this->__code, $tag );

}

$info = debug_backtrace();

if( !is_array($info) ){

return null;

}

// 找到调用文件索引 ( 这里是通过文件名匹配的，如果改了文件名请自行修改这段代码 )

$index = -1;

foreach( $info as $counter => $item ){

if( isset($item['file']) ){

if( stripos($item['file'], 'SQLTools.class.php') > 0 ){

$index = $counter + 1; // 下一个item即调用文件

break;

}

}

}

// 没有找到调用信息

if( $index === -1 ){

return null;

}

// 堆栈中没有找到相关信息

$caller = $info[$index];

if( !isset($caller['file']) || !file_exists($caller['file']) || !isset($caller['line']) ){

return null;

}

$line = $caller['line'];

$file = @fopen( $caller['file'], "r" );

$counter = 1;

$code = '';

while( ($buffer = fgets($file)) !== false ){

if( $counter >= $line ){

$code .= $buffer;

if( substr( $buffer, -2, 1 ) == ';' ){

goto end;

}

}

$counter++;

}

end: isset( $file ) && @fclose( $file );

$code = str_replace( ' ', '', $code );

$code = str_replace( "\t", '', $code );

$code = str_replace( "\n", '', $code );

$code = explode( '->', $code );

return $this->__createResult( $code, $tag );

}

// 返回$this起到链接作用，又判断当前调用tag是否已经结束

private function __createResult( $code, $tag ){

$this->__code = $code;

foreach( $this->__code as $code){

if( stripos($code, $tag) === 0 && substr( $code, -1 ) === ';' ){ // 判断查询结束

return $this->__query( $tag );

}

}

return $this;

}

}