How do I lock read/write to MySQL tables so that I can select and then insert without other programs reading/writing to the database?

Question

I am running many instances of a webcrawler in parallel.

Each crawler selects a domain from a table, inserts that url and a start time into a log table, and then sta

Answer 1

I got some inspiration from @Eljakim's answer and started this new thread where I figured out a great trick. It doesn't involve locking anything and is very simple.

INSERT INTO crawlLog (companyId, timeStartCrawling)
SELECT id, now()
FROM companies
WHERE id NOT IN
(
    SELECT companyId
    FROM crawlLog AS crawlLogAlias
)
LIMIT 1