Welcome to OStack Knowledge Sharing Community for programmer and developer-Open, Learning and Share
Welcome To Ask or Share your Answers For Others

Categories

0 votes
779 views
in Technique[技术] by (71.8m points)

mysql - Execute INSERT if table is empty?

Is there a way to do an insert under a count condition, something like:

INSERT INTO my_table (colname) VALUES('foo') IF COUNT(my_table) < 1

Basically I want to insert a single default record if the table is currently empty. I'm using mysql.

See Question&Answers more detail:os

与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…
Welcome To Ask or Share your Answers For Others

1 Answer

0 votes
by (71.8m points)

Use SELECT instead of VALUES to be able to expand the query with a WHERE clause.

EXISTS is a better & faster test than COUNT

INSERT INTO my_table (colname)
SELECT 'foo'
WHERE NOT EXISTS (SELECT * FROM my_table)

与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…
Welcome to OStack Knowledge Sharing Community for programmer and developer-Open, Learning and Share
Click Here to Ask a Question

...