On 06 Apr 2017 at 13:19, Simon Slavin <slav...@bigfraud.org> wrote: > On 6 Apr 2017, at 12:11pm, Tim Streater <t...@clothears.org.uk> wrote: > >> When my app starts, I check that the file in question actually *is* a >> database by doing some simple steps like open, selects from important tables, >> and a read/write to a globals table in the database that contains, for >> instance, the version number. > > Don’t do this. Because if the file isn’t there, or if the file is there > but has zero length, SQLite will turn it into a SQLite file and then return > results which don’t let you tell whether the file was already there or just > created. And you probably don't want this.
That would appear not to be the case. Under OS X 10.9.5, I touched a non-existent file and then using sqlite3.app did: .schema <--- gave nothing select version from globals; <--- gave "Error: no such table" My file stayed at zero bytes long. I then added a bit of text to the file and repeating the exercise: .schema <--- gave nothing select version from globals; <--- gave "Error: file is encrypted or is not a database" The file was not modified by these actions. > Instead use PHP functions to check that the file exists using PHP function > "file_exists()" and then using fread() to read the first 16 bytes from it. > Those 16 bytes should be "SQLite format 3" followed by a 0x00 byte for a > string terminator. Actually I am scanning the directory and examining all the files there. The sequence of tests is: open, read from the two expected tables, write back to one of them. This confirms that the file is a database, it's one I'm looking for, it has the expected tables, and is writeable too. I keep a database of such files which is then re-populated with successful entries. This sequence was subject to careful testing when I first wrote it. Each step is under try/catch and I only proceed to the next step if previous ones succeeded. > I’m not sure what you mean by "unconfigured" so I’ll let other people > write about that, or you can post to clarify. I'm not sure either, better ask the OP. -- Cheers -- Tim _______________________________________________ sqlite-users mailing list sqlite-users@mailinglists.sqlite.org http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users
