Mysql How to only select from a column if the column exists - mysql

Question

I need to be able to check if a column exists and if it does then I want to SELECT from it.
I am trying lots of different variations but I'm not even sure if this is possible.
Here's my latest attempt:
SELECT
IF (EXISTS (SELECT `Period` AS `Period` FROM myview), `PERIOD`,
IF (EXISTS (SELECT `Country` AS `COUNTRY` FROM myview),`COUNTRY` FROM myview ;
Any ideas?
EDIT
I had seen the other question on here: MySQL, Check if a column exists in a table with SQL
But I still struggle with the if statement. I can check to see if the column exists using the answer in the question above. But my question is - how to execute a select statement from that column if the result is found to be true.
EDIT 2
The answer below indicates that I should use the BEGIN and END statement and this makes sense. However, my query complains at the first line. It says 'unexpected IF' - can anybody confirm if this is the right syntax fro MYSQL?
if( exists (SELECT *
FROM information_schema.COLUMNS
WHERE TABLE_SCHEMA = 'db_name'
AND TABLE_NAME = 'view_name'
AND COLUMN_NAME = 'column_name') )
begin
SELECT `column_name` FROM `view_name`
end
Thanks in advance.

Answer 1

This query will give you whether a column exists.
SELECT *
FROM information_schema.COLUMNS
WHERE
TABLE_SCHEMA = 'db_name'
AND TABLE_NAME = 'table_name'
AND COLUMN_NAME = 'column_name'
If you want to check if some columns exist then perform a select statement you need to first check your columns exist. Then perform the select:
if (exists (SELECT * FROM information_schema.COLUMNS WHERE TABLE_NAME = 'myview' AND COLUMN_NAME = 'Period') and exists (SELECT * FROM information_schema.COLUMNS WHERE TABLE_NAME = 'myview' AND COLUMN_NAME = 'Country'))
begin
select `Period`, `Country` from myview
end
If the IF condition is true, then you will execute anything inside the BEGIN and END.

Answer 2

I came across the same situation where I had some product tables created by sheets uploaded by users. Sometimes, the sheets did not have column named "obsolete", so I had to import all products from the sheet but not the obsolete ones.
I am not modifying my query based on the original question that was asked, but here is my solution:
SELECT
t2.model,
(
SELECT
COUNT(*) AS _count
FROM db.table t1
WHERE
`obsolete`=1
AND t1.model=t2.model
) AS `obsolete`
FROM (
SELECT
0 AS `obsolete`,
t3.model
FROM db.table t3
) t2
There are 2 most important parts in this query:
We are selecting 0 AS obsolete as dummy to fool MySql which will be used even if column does not exist when selecting COUNT(*).
We have named tables as t1 & t2 to match the column model as t1.model=t2.model.