Model: Default (GPT-3.5)
I have a MySQL database with two tables -- items and subscriptions. items have fields feedUrl, pubDate and flDeleted. subscriptions have fields feedUrl and listName.

Okay, how can I assist you with these tables? Do you have any specific question or task that you need help with?

i want a MySQL query that returns * from items whose feedUrl matches subscriptions whose listname is "davewiner"

You can use a JOIN query to combine the items and subscriptions tables based on the feedUrl column and filter the result by the listName value 'davewiner'. Here's an example query that should achieve what you're looking for:

vbnet
SELECT items.*
FROM items
JOIN subscriptions ON items.feedUrl = subscriptions.feedUrl
WHERE subscriptions.listName = 'davewiner';

This query joins the two tables on the feedUrl column, filters the results by subscriptions with listName equal to 'davewiner', and selects all columns (*) from the items table for the matching rows.

great. now have it order the result by pubDate in descending order, limit of 175.

Sure! Here's an updated query that includes the ORDER BY and LIMIT clauses to sort the results by pubDate in descending order and limit the output to 175 rows:

vbnet
SELECT items.*
FROM items
JOIN subscriptions ON items.feedUrl = subscriptions.feedUrl
WHERE subscriptions.listName = 'davewiner'
ORDER BY items.pubDate DESC
LIMIT 175;

This query first filters the results by subscriptions with listName equal to 'davewiner', joins the two tables on the feedUrl column, and then sorts the resulting items by pubDate in descending order. Finally, the LIMIT clause is used to limit the output to the top 175 rows.

it's too slow. should i add some indexes? if so what should be indexed?

Yes, adding indexes to your tables can significantly improve query performance. In this case, you can improve the performance of the query by adding indexes on the feedUrl column of both tables and the pubDate column of the items table.

Here are the CREATE INDEX statements to add these indexes:

arduino
CREATE INDEX feedUrl_items ON items (feedUrl);
CREATE INDEX feedUrl_subscriptions ON subscriptions (feedUrl);
CREATE INDEX pubDate_items ON items (pubDate);

These statements will create indexes on the feedUrl column of both tables and the pubDate column of the items table. With these indexes in place, the database can perform more efficient lookups and sorting when executing the query, which should result in improved performance.

Note that adding indexes to a table can impact insert and update performance, as the database needs to update the indexes in addition to the table data. However, the benefits of improved query performance often outweigh the costs of slower insert/update performance.