help on the select statement

three table
t1 one col with 3 row
1
2
3t2 two col one row
25t3 one col with 4 row
1
2
3
4I would like to insert the value from t1 into t3, but need to checking the duplicate value for col1 with t2 if it matches, then will use t2.col2 vaule,
if not match, will add 100 as the new value
so value for insert will be
101
5
103Here is the script:insert
into t1 values( 3)--select * from t1create
table t2 ( c1 int, c2 int )insert
into t2 values( 2, 5)--select * from t2create
table t3 ( c1 int)insert
into t3 values( 1)insert
into t3 values( 2)insert
into t3 values( 3)insert
into t3 values( 4)--select * from t3
Here is my code, but it returns error as The multi-part identifier "t2.c2" could not be bound.select
c1=case when exists ( select t2.c1 from t2
where t2.c1=t1.c1 ) then t2.c2else
c1+100end
from
t1
Thanks for help