How to create a new column using existing column in SQL Redshift - sql

Question

I am trying to create a new column in SQL with certain conditions in DBVisualizer by connecting redshift data source.
I used the following command to achieve the results but getting syntax error.
I would be really grateful for any help.
Code:
select existing_col, if(existing_col like '%LM%','LM',if(referrer like
'%LH%','LH',if(existing_col like '%HT%','HT',if(existing_col like '%M_App%','LM','Other
Business Lines'))))
AS derived_variable from
db.table_name;
Error:
[Code: 0, SQL State: 42883] ERROR: function if(boolean, "unknown", "unknown") does not exist
Hint: No function matches the given name and argument types. You may need to add explicit type casts.
select existing_col,
if(existing_col like '%LM%','LM',if(existing_col like '%LH%','LH',if(existing_col like '%HT%','HT',if(existing_col like '%Mint_App%','LM','Other Business Lines'))))
AS derived_variable from
db.table_name
Expected Output:
existing_col derived_variable
PB Other
OTT Other
Mint_App LM
LSLM LM
LMG LM
HTTC HT
KLH LH
Thanks.

Answer 1

As stated in the error message, the IF() function does not exist in Redshift. Therefore, you should use CASE:
select
existing_col,
case
when existing_col like '%LM%' or existing_col like '%Mint_App%' then 'LM'
when existing_col like '%LH%' then 'LH'
when existing_col like '%HT%' then 'HT'
else 'Other'
end as derived_variable
from db.table_name