USE my_tutorial; SELECT * FROM dt_table_tm; SELECT * FROM `dt_table_tm` WHERE tm>=DATE_SUB(NOW(), INTERVAL 24 HOUR); # 1 SELECT * FROM `dt_table_tm` WHERE tm BETWEEN DATE_SUB(NOW(), INTERVAL 24 HOUR) AND NOW(); # 2 SELECT * FROM `dt_table_tm` WHERE tm>=DATE_SUB(NOW() , INTERVAL '12:30' HOUR_MINUTE); # 3 SELECT * FROM `dt_table_tm` WHERE HOUR(tm) BETWEEN 13 AND 14; # 4 SELECT * FROM `dt_table_tm` WHERE DATE(tm)='2020-09-27' AND HOUR(tm) BETWEEN 13 AND 14; #5 SELECT * FROM `dt_table_tm` WHERE TIME(tm) BETWEEN TIME('11:45:22') AND TIME('14:11:14'); #6 SELECT * FROM `dt_table_tm` WHERE DATE(tm)='2020-09-27' AND TIME(tm) BETWEEN TIME('11:45:22') AND TIME('14:11:14'); #7 SELECT HOUR(tm),COUNT(*) as No FROM `dt_table_tm` GROUP BY HOUR(tm); #8 SELECT HOUR(tm),COUNT(*) as No FROM `dt_table_tm` WHERE DATE(tm)='2020-09-30' GROUP BY HOUR(tm); # 9 SELECT DATE(tm),COUNT(*) as No FROM `dt_table_tm` WHERE HOUR(tm) BETWEEN 13 AND 14 GROUP BY DATE(tm); #10 SELECT COUNT(*) FROM `dt_table_tm` WHERE DATE(tm)='2020-09-30' AND HOUR(tm) BETWEEN 13 AND 14; # 11 SELECT DATE(tm),MAX(tm) as Last_record FROM `dt_table_tm` GROUP BY DATE(tm); # 12 SELECT DATE(tm),MIN(tm) as Last_record FROM `dt_table_tm` GROUP BY DATE(tm); # 13