Question

I want to retrieve the columns from the table., depending on the conditions.,
what I can use.

For example, I’ ve fields namely, add order comments, cancel order comments, postpone order comments, action(add, cancel, postpone) and amount received(Y/N)

Now I’ve to fetch columns add order comments, cancel order comments, postpone order comments depending on action and amount received.,

if(action='add' and amount received='Y')
then
i've to fetch add order comments column
elseif(action='postpone' and amount received='Y')
then
i've to fetch postpone order comments column
else (action='cancel')
then i've to fetch cancel order comments

how to get this done in sql or plsql., I want this conditions in select statement

Answer 1

Note that by “sql or plsql” I’m assuming that “sql” refers to T-SQL as used by MS SQL Server. If not, please use the appropriate equivalent in your language.

You need to use a CASE (T-SQL) statement (PL-SQL equivalent)

For example, in T-SQL:

SELECT OrderId AS OrderId
       CASE 
           WHEN Action = 'add' AND amountRcd = 'Y' THEN addOrderComment
           WHEN Action = 'postpont' AND amountRcd = 'Y' THEN postponeOrderComment
           WHEN Action = 'cancel' THEN cancelOrderComment 
           ELSE 'Unrecognised action'
       END AS Comment
FROM tblOrders

Note also that in the rules you’ve given, if the amountRcd field is not Y, then you will get “Unrecognised action” as the comment. I think you may need to clarify your rules to prevent this.