if not exists(select ID from jc_mobile_area_contrast where num = '1300000')
insert into jc_mobile_area_contrast(num,city)VALUES('1300000','北京')
------解决方案--------------------------------------------------------
insert into jc_mobile_area_contrast(num,city) VALUES('1300000','北京') WHERE NOT EXISTS (SELECT * FROM jc_mobile_area_contrastWHERE id = 1300000);
Sql server和mysql语法不一样