Update with Join Pattern

Consider a production table called questions_mysql and a table iwtQuestions (imported worktable) representing the last batch of imported CSV data from a LOAD DATA INFILE. The worktable is truncated before the import, the data is imported, and that process is not shown here.

Update our production data using a join to our imported worktable data.

UPDATE questions_mysql q -- our real table for production 
join iwtQuestions i -- imported worktable 
ON i.qId = q.qId
SET q.closeVotes = i.closeVotes,
	q.votes = i.votes, 
	q.answers = i.answers, 
	q.views = i.views;

Aliases q and i are used to abbreviate the table references. This eases development and readability.

qId, the Primary Key, represents the Stackoverflow question id. Four columns are updated for matching rows from the join.