pivot转换表

create table #a_aa_a(
t_id int,
t_uesrid INT ,
t_time varchar(10)
)
insert into #a_aa_a VALUES  (1,1,'20200101')
insert into #a_aa_a VALUES  (2,1,'20210101')
insert into #a_aa_a VALUES  (3,1,'20220101')
insert into #a_aa_a VALUES  (4,2,'20210101')
insert into #a_aa_a VALUES  (5,2,'20220101')
insert into #a_aa_a VALUES  (6,2,'20230101')
insert into #a_aa_a VALUES  (7,3,'20210101')
insert into #a_aa_a VALUES  (8,3,'20220101')
insert into #a_aa_a VALUES  (9,3,'20230101')

select a.t_name,count(a.[20210401]) [20210401],count(a.[20210403]) [20210403],count(a.[20210405]) [20210405],count(a.[20210408]) [20210408] 
from #a_aa_a
pivot(
sum(t_grade) 
for
t_date
in([20210401],[20210403],[20210405],[20210408])
)as a
group by a.t_name
--其实就是一个表间接生成一个临时的group by分组的一个表

测试版本