How to remove "Tab" from column data (SQL)

Problem:
Remove leading or trailing "Tab" from data values
Eg:
ColumnA

    val1
val2
val3
    val4
val5

So to remove these "tab" from data values we cannot use trim function directly

update testtable set ColumnA=trim(ColumnA);

Solution:
To solve this problem we can slightly modify the trim function and include Replace function also in it by specifying ascii value of "tab" which is 9.

update testtable set ColumnA=trim(replace(ColumnA,Char(9),Char(32)));

How to Apply DISTINCT condition on only one Column

Problem:- Lot of time we need to apply Distinct on only one column, but the DISTINCT keyword doesn't provided by SQL applies distinct to whole row.

Solution:- The following query can solve the problem.

Select * from TestTable T where Testno IN(Select MAX(Testno) from TestTable where T.Testname=Testname)

In this query Testno is the Testname is the column by which you want to distinct the rows, and Testno is the column which is not distinct (for e.g. Primary key)