在列中查找不同的值并在sql中添加另一列

Question

If I have a table with columns a and b as shown

a b
1 1
1 10
1 20
2 11
2 21
3 31

I want to insert into this table the distinct values in column a along with an arbitrary constant, let's say 0. So I want the output to be:

a b
1 1
1 10
1 20
2 11
2 21
3 31
1 0
2 0
3 0

How can I use INSERT INTO with DISTINCT to accomplish this? I'm not sure how to incorporate the arbitrary constant

Answer 1

只需按照您所说的，插入选择区：

insert into tablename select distinct a, 0 from tablename

Answer 2

Pretty straightforward:

insert into your_Table (a, b)
select distinct a, 0
from your_Table