请教各位老师，如何编程把以下tt1表规定时段变成 tt2表
SET DATE TO ansi
SET CENTURY on
SET SAFETY off
CREATE table tt1 (cname c(6),cyear c(6), cmonth c(6),nnewsal n (9,2))
INSERT INTO tt1 VALUES ("hans", "1998","2",300)
INSERT INTO tt1 VALUES ("hans", "1998","3",300)
INSERT INTO tt1 VALUES ("hans", "1998","4",300)
INSERT INTO tt1 VALUES ("hans", "1998","5",300)
INSERT INTO tt1 VALUES ("hans", "1998","6",300)
INSERT INTO tt1 VALUES ("hans", "1998","7",1400)
INSERT INTO tt1 VALUES ("hans", "1998","8",1400)
INSERT INTO tt1 VALUES ("hans", "1998","9",1400)
INSERT INTO tt1 VALUES ("hans", "1998","10",1400)
INSERT INTO tt1 VALUES ("hans", "1998","11",1400)
INSERT INTO tt1 VALUES ("hans", "1998","12",1400)
INSERT INTO tt1 VALUES ("hans", "1999","1",1400)
INSERT INTO tt1 VALUES ("hans", "1999","2",1400)
INSERT INTO tt1 VALUES ("hans", "1999","3",1400)
INSERT INTO tt1 VALUES ("hans", "1999","4",1400)
INSERT INTO tt1 VALUES ("hans", "1999","5",1400)
INSERT INTO tt1 VALUES ("hans", "1999","6",1400)
INSERT INTO tt1 VALUES ("hans", "1999","7",1500)
INSERT INTO tt1 VALUES ("hans", "1999","8",1500)
INSERT INTO tt1 VALUES ("hans", "1999","9",1500)
INSERT INTO tt1 VALUES ("hans", "1999","10",1500)
INSERT INTO tt1 VALUES ("hans", "1999","11",1500)
INSERT INTO tt1 VALUES ("hans", "1999","12",1500)
INSERT INTO tt1 VALUES ("hans", "2000","1",1500)
INSERT INTO tt1 VALUES ("hans", "2000","2",1500)
INSERT INTO tt1 VALUES ("hans", "2000","3",1500)
INSERT INTO tt1 VALUES ("hans", "2000","4",1500)
INSERT INTO tt1 VALUES ("hans", "2000","5",1500)
INSERT INTO tt1 VALUES ("hans", "2000","6",1500)
INSERT INTO tt1 VALUES ("hans", "2000","7",5000)
INSERT INTO tt1 VALUES ("hans", "2000","8",5000)
INSERT INTO tt1 VALUES ("hans", "2000","9",5000)
INSERT INTO tt1 VALUES ("hans", "2000","10",5000)
INSERT INTO tt1 VALUES ("hans", "2000","11",5000)
INSERT INTO tt1 VALUES ("hans", "2000","12",5000)
INSERT INTO tt1 VALUES ("hans", "2001","1",5000)
INSERT INTO tt1 VALUES ("dick", "1999","5",200)
INSERT INTO tt1 VALUES ("dick", "1999","6",200)
INSERT INTO tt1 VALUES ("dick", "1999","7",800)
INSERT INTO tt1 VALUES ("dick", "1999","8",800)
INSERT INTO tt1 VALUES ("dick", "1999","9",800)
INSERT INTO tt1 VALUES ("dick", "1999","10",800)