SELECT T1.agency_id ,  T2.agency_details FROM Staff AS T1 JOIN Agencies AS T2 ON T1.agency_id  =  T2.agency_id GROUP BY T1.agency_id ORDER BY count(*) DESC LIMIT 1
Return the id and detail for the agency with the most staff.
CREATE TABLE `Agencies` (
`agency_id` INTEGER PRIMARY KEY,
`agency_details` VARCHAR(255) NOT NULL
);
CREATE TABLE `Staff` (
`staff_id` INTEGER PRIMARY KEY,
`agency_id` INTEGER NOT NULL,
`staff_details` VARCHAR(255) NOT NULL
);
CREATE TABLE `Clients` (
`client_id` INTEGER PRIMARY KEY,
`agency_id` INTEGER NOT NULL,
`sic_code` VARCHAR(10) NOT NULL,
`client_details` VARCHAR(255) NOT NULL,
FOREIGN KEY (`agency_id` ) REFERENCES `Agencies`(`agency_id` )
);
INSERT INTO Clients (`client_id`, `agency_id`, `sic_code`, `client_details`) VALUES (1, 8, 'Mutual', 'Alta');
CREATE TABLE `Invoices` (
`invoice_id` INTEGER PRIMARY KEY,
`client_id` INTEGER NOT NULL,
`invoice_status` VARCHAR(10) NOT NULL,
`invoice_details` VARCHAR(255) NOT NULL,
FOREIGN KEY (`client_id` ) REFERENCES `Clients`(`client_id` )
);
CREATE TABLE `Meetings` (
`meeting_id` INTEGER PRIMARY KEY,
`client_id` INTEGER NOT NULL,
`meeting_outcome` VARCHAR(10) NOT NULL,
`meeting_type` VARCHAR(10) NOT NULL,
`billable_yn` VARCHAR(1),
`start_date_time` DATETIME,
`end_date_time` DATETIME,
`purpose_of_meeting` VARCHAR(255),
`other_details` VARCHAR(255) NOT NULL,
FOREIGN KEY (`client_id` ) REFERENCES `Clients`(`client_id` )
);
CREATE TABLE `Payments` (
`payment_id` INTEGER NOT NULL ,
`invoice_id` INTEGER NOT NULL,
`payment_details` VARCHAR(255) NOT NULL,
FOREIGN KEY (`invoice_id` ) REFERENCES `Invoices`(`invoice_id` )
);
CREATE TABLE `Staff_in_Meetings` (
`meeting_id` INTEGER NOT NULL,
`staff_id` INTEGER NOT NULL,
FOREIGN KEY (`meeting_id` ) REFERENCES `Meetings`(`meeting_id` ),
FOREIGN KEY (`staff_id` ) REFERENCES `Staff`(`staff_id` )
);
INSERT INTO Agencies (`agency_id`, `agency_details`) VALUES (1, 'Heller-Muller')
INSERT INTO Staff (`staff_id`, `agency_id`, `staff_details`) VALUES (1, 6, 'Rubie')
INSERT INTO Clients (`client_id`, `agency_id`, `sic_code`, `client_details`) VALUES (2, 5, 'Bad', 'Mac')
INSERT INTO Invoices (`invoice_id`, `client_id`, `invoice_status`, `invoice_details`) VALUES (1, 5, 'Working', 'excellent')
INSERT INTO Meetings (`meeting_id`, `client_id`, `meeting_outcome`, `meeting_type`, `billable_yn`, `start_date_time`, `end_date_time`, `purpose_of_meeting`, `other_details`) VALUES (1, 15, 'Report', 'Team', '0', '2018-03-06 05:07:33', '2018-03-21 09:26:41', 'get proposal done', '0')
INSERT INTO Payments (`payment_id`, `invoice_id`, `payment_details`) VALUES (1, 3, 'MasterCard')
INSERT INTO Staff_in_Meetings (`meeting_id`, `staff_id`) VALUES (6, 7)