How to use SQL alias within query - mysql

Question

I have a sql query (below) to insert records into a database. The goal is to insert only new / unique entries in the database. So it will insert the row if the row doesn't already exist in the entire database. I would like to have it evaluate that row against ONLY the rows that have the symbol in the instrumentSymbol, rather than evaluating against every row in the entire database.
I am running into this syntax error which I have pinpointed to be due to the use of an alias in line SELECT 1 FROM instrumentsHistory WHERE instrumentSymbol = 'ZYME' AS f
This query works fine if removing the WHERE instrumentSymbol = {SYMBOL} conditional, but I need to this to refine the set of records the query compares itself to (thus reducing time to complete task.
I have looked through the documentation which leads me to believe there is nothing wrong with this query. Can someone pls point me in the right direction?
The Error:
(sqlite3.OperationalError) near "AS": syntax error
[SQL: INSERT INTO instrumentsHistory (datetime, instrumentSymbol, observation, observationColName)
SELECT t.datetime, t.instrumentSymbol, t.observation, t.observationColName
FROM tempTable t
WHERE NOT EXISTS
(SELECT 1 FROM instrumentsHistory WHERE instrumentSymbol = 'ZYME' AS f
WHERE t.datetime = f.datetime
AND t.instrumentSymbol = f.instrumentSymbol
AND t.observation = f.observation
AND t.observationColName = f.observationColName)]
EDIT 1:
Adding complete query...
sql = f"""INSERT INTO instrumentsHistory (datetime, instrumentSymbol, observation, observationColName)
SELECT t.datetime, t.instrumentSymbol, t.observation, t.observationColName
FROM tempTable t
WHERE NOT EXISTS
(SELECT 1 FROM instrumentsHistory WHERE instrumentSymbol = '{symbol}' AS f
WHERE t.datetime = f.datetime
AND t.instrumentSymbol = f.instrumentSymbol
AND t.observation = f.observation
AND t.observationColName = f.observationColName)"""

Answer 1

This code:
WHERE NOT EXISTS (SELECT 1 FROM instrumentsHistory WHERE instrumentSymbol = 'ZYME' AS f
WHERE t.datetime = f.datetime
has multiple errors. There are two WHERE clauses in a row. And as is being used in a WHERE clause. I am guessing this is a copy-and-past error, but it is unclear what you intend.