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
187 views
in Technique[技术] by (71.8m points)

How do I check in SQLite whether a table exists?

How do I, reliably, check in SQLite, whether a particular user table exists?

I am not asking for unreliable ways like checking if a "select *" on the table returned an error or not (is this even a good idea?).

The reason is like this:

In my program, I need to create and then populate some tables if they do not exist already.

If they do already exist, I need to update some tables.

Should I take some other path instead to signal that the tables in question have already been created - say for example, by creating/putting/setting a certain flag in my program initialization/settings file on disk or something?

Or does my approach make sense?

Question&Answers: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)

I missed that FAQ entry.

Anyway, for future reference, the complete query is:

SELECT name FROM sqlite_master WHERE type='table' AND name='{table_name}';

Where {table_name} is the name of the table to check.

Documentation section for reference: Database File Format. 2.6. Storage Of The SQL Database Schema

  • This will return a list of tables with the name specified; that is, the cursor will have a count of 0 (does not exist) or a count of 1 (does exist)

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

...