How to series TSQL 2

6. How to find second highest

SELECT COL 
FROM TABLE 
ORDER BY COL DESC
OFFSET 1 ROWS
FETCH NEXT 1 ROWS ONLY;


7. How to use multiple cte

;with cte1
as
(select col1, null as col2 from Tab),

cte2
as 
(
select col2, null as col1 from Tab
)

select * from cte1
union
select * from cte2

8 How to rename column
EXEC sp_rename 'TABLENAME.OLD_COLUMNNAME', 'NEW_COLUMNAME', 'COLUMN';
.