mssql如何避免插入重复数据

alter table 你的表名 add constraint cons_01 unique (重复列名一,重复列名二,重复列名三,重复列名四,重复列名五)

if not exists(select 1 from tb where 重复列名一='xx' and 重复列名二='xx' and 重复列名三='xx' and 重复列名四='xx')
begin
    insert into ...
end