CREATE TABLE TableA (
    datemessage	DATETIME2,
    id_tasks NVARCHAR(255),
    Whowritedmessage NVARCHAR(255)
);

INSERT INTO TableA VALUES('2017-11-01 04:59:07.6140000', 'C56D5EF0-CBC4-473F-90A7-A7A10223AE3E', 'Client');
INSERT INTO TableA VALUES('2017-11-01 05:05:17.5000000', 'C56D5EF0-CBC4-473F-90A7-A7A10223AE3E', 'Client');
INSERT INTO TableA VALUES('2017-11-01 05:06:53.9090000', 'C56D5EF0-CBC4-473F-90A7-A7A10223AE3E', 'Agent');
INSERT INTO TableA VALUES('2017-11-01 05:06:53.9090000', 'C56D5EF0-CBC4-473F-90A7-A7A10223AE3E', 'Agent');
INSERT INTO TableA VALUES('2017-11-01 05:07:18.7020000', 'C56D5EF0-CBC4-473F-90A7-A7A10223AE3E', 'Client');
INSERT INTO TableA VALUES('2017-11-01 05:07:43.1280000', 'C56D5EF0-CBC4-473F-90A7-A7A10223AE3E', 'Agent');
INSERT INTO TableA VALUES('2017-11-01 05:07:59.5780000', 'C56D5EF0-CBC4-473F-90A7-A7A10223AE3E', 'Client');
INSERT INTO TableA VALUES('2017-11-01 05:09:55.0630000', 'C56D5EF0-CBC4-473F-90A7-A7A10223AE3E', 'Client');
INSERT INTO TableA VALUES('2017-11-01 05:14:12.5870000', 'C56D5EF0-CBC4-473F-90A7-A7A10223AE3E', 'Agent');
INSERT INTO TableA VALUES('2017-11-01 05:14:56.3690000', 'C56D5EF0-CBC4-473F-90A7-A7A10223AE3E', 'Client');
INSERT INTO TableA VALUES('2017-11-01 06:06:56.1080000', 'C56D5EF0-CBC4-473F-90A7-A7A10223AE3E', 'Agent');
INSERT INTO TableA VALUES('2017-11-01 06:07:07.2790000', 'C56D5EF0-CBC4-473F-90A7-A7A10223AE3E', 'Agent');
INSERT INTO TableA VALUES('2017-11-01 06:21:17.5480000', 'C56D5EF0-CBC4-473F-90A7-A7A10223AE3E', 'Client');
INSERT INTO TableA VALUES('2017-11-01 06:21:38.4280000', 'C56D5EF0-CBC4-473F-90A7-A7A10223AE3E', 'Agent');