I need to find an open spot in the calendar (MYSQL) and allocate that time and date to a job/work order - mysql

Question

I need to find an open date time in the future and allocate that time in the calendar for that employee based on his/her worktimes Thanks in advance
I have a calendar table, employee(recourse) table ,employee working times and jobs (with Duration)
CREATE TABLE `calendar` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`Subject` varchar(200) DEFAULT NULL,
`DateField` date DEFAULT NULL,
`EndDate` date DEFAULT NULL,
`TimeField` time DEFAULT NULL,
`EndTime` time DEFAULT NULL,
`job_id` int(11) DEFAULT NULL,
`recourse_employee_id` int(11) DEFAULT NULL,
PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=1902 DEFAULT CHARSET=utf8;
CREATE TABLE `rc_resources_employee` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`name` varchar(255) DEFAULT NULL,
`categoryid` int(11) DEFAULT NULL,
`login_user_id` int(11) DEFAULT NULL,
PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=6 DEFAULT CHARSET=utf8;
CREATE TABLE `jobs` (
`Job_ID` int(11) NOT NULL AUTO_INCREMENT,
`Job_Subject` varchar(150) DEFAULT NULL,
`Job_Description` mediumtext,
`Job_Start_Date` date DEFAULT NULL,
`Job_End_Date` date DEFAULT NULL,
`Job_Duration` float DEFAULT NULL,
`Job_Start_Time` time DEFAULT NULL,
`Job_End_Time` time DEFAULT NULL,
`Job_employee` int(11) DEFAULT NULL,
PRIMARY KEY (`Job_ID`)
) ENGINE=InnoDB AUTO_INCREMENT=1875 DEFAULT CHARSET=utf8;
CREATE TABLE `work_hours` (
`wh_id` int(11) NOT NULL AUTO_INCREMENT,
`recourse_id` int(11) unsigned NOT NULL,
`wh_day_of_week` int(11) unsigned NOT NULL,
`wh_start_time` time NOT NULL,
`wh_end_time` time NOT NULL,
PRIMARY KEY (`wh_id`)
) ENGINE=InnoDB AUTO_INCREMENT=8 DEFAULT CHARSET=utf8;