sql 优化select distinct ikey_ key idescription ftriggerid triggerId -- hhostfrom items ileft join hosts h on ihostid = hhostidleft join functions f on iitemid = fitemidwhere fitemid is not null and fnam

To optimize the given SQL query, you can follow the following steps:

1. Remove the unnecessary backticks around the column aliases (key, triggerId).
2. Remove the unnecessary comment (-- h.host) from the query.
3. Use INNER JOIN instead of LEFT JOIN for the table "hosts" since the condition "f.itemid is not null" already filters out the rows where there is no matching host.
4. Add appropriate indexes on the columns being used in JOIN conditions and WHERE clause.

The optimized SQL query would be:

SELECT DISTINCT i.key_, i.description, f.triggerid AS triggerId
FROM items i
INNER JOIN hosts h ON i.hostid = h.hostid
LEFT JOIN functions f ON i.itemid = f.itemid
WHERE f.itemid IS NOT NULL AND f.name <> 'nodata';

Make sure to create indexes on the columns "items.hostid", "hosts.hostid", "functions.itemid", and "functions.name" for better performance