For a time range, like a time card entry, check that input range of time is valid, and check against a table with times entered to avoid overlap; Allow times to "touch" in a minute range.

TimeCardValidRange.php

/**
 * @brief Check for Valid Time In and Out
 * 
 * @params arr(in_time, out_time, technichian_id);
 * @return json (success,message);
 */
    private function isValidRange($params)
    {
         // validate input
        if ($params["in_time"] == "1969-12-31 19:00") die("{'success': false, 'message': 'Incorrect Time In.'}");
        if ($params["out_time"] == "1969-12-31 19:00") die("{'success': false, 'message': 'Incorrect Time Out.'}");
        if ($params["in_time"] == $params["out_time"]) die("{'success': false, 'message': 'Out is In.'}");
        if ($params["in_time"] > $params["out_time"]) die("{'success': false, 'message': 'Greater In than Out Time.'}");
        if (!$this->isOpenRange($params))  die("{'success': false, 'message': 'Time Range Overlap'}");
    }

/**
 * @brief Check Entry Against Existing Time Periods
 * 
 * @params arr(in_time, out_time, technichian_id);
 * @return bool
 */

    private function isOpenRange($params) 
    {
        try{
            $in_time = new DateTime($params["in_time"]);
            $out_time = new DateTime($params["out_time"]);
            $in_time->add(new DateInterval('PT1M'));
            $out_time->sub(new DateInterval('PT1M'));
            
        // pad with 1 second to allow touching times;
            $adjusted_in_time=$in_time->format("Y-m-d H:i");
            $adjusted_out_time=$out_time->format("Y-m-d H:i");
          
            $_bind = array(
                new Database_BindParam(":technician_id", $params["technician_id"], PDO::PARAM_INT),
                new Database_BindParam(":in_time", $adjusted_in_time, PDO::PARAM_STR),
                new Database_BindParam(":out_time", $adjusted_out_time, PDO::PARAM_STR),
                new Database_BindParam(":in_time2", $adjusted_in_time, PDO::PARAM_STR),
                new Database_BindParam(":out_time2", $adjusted_out_time, PDO::PARAM_STR)
            );
            
            $SQLisOpenRange = "--
                SELECT 
                    a.technician_id, 
                    a.record_id, 
                    a.in_time, 
                    a.out_time
                FROM service_time_card a
                WHERE (
                    a.in_time  BETWEEN  :in_time AND  :out_time
                    OR
                    a.out_time BETWEEN  :in_time2 AND  :out_time2
                )
                AND technician_id = :technician_id";
           
            $rs = $this->db->query($SQLisOpenRange,$_bind);
            $result = $this->db->fetch($rs);
                  
            $msg = $SQLisOpenRange;
            $msg .= ";".$tehcnician_id .":" . $adjusted_in_time .":". $adjusted_out_time;
            
            if($result["technician_id"] == $params["technician_id"]) return false;
            else return true;
        
        } catch (Exception $_e){
            MelodicException::kill($_e,true,$msg);
        }

    }