Question

I have this weird problem. I have defined a column in a SQLite database as STRING but when I use it with integers prefixed by a + it automatically converts them to a proper integer:

sqlite> create table test (key STRING);
sqlite> insert into test values ('+1'); 
sqlite> insert into test values ("+2");
sqlite> select * from test;
1
2

As you can see the + sign is removed. On the other hand, if I quote the strings twice:

sqlite> delete from test;
sqlite> insert into test values ('"+3"');
sqlite> insert into test values ("'+4'");
"+3"
'+4'

… it works as expected but they are quoted. My primary problem is that I need to “double quote” all strings because I cannot guarantee that some string might look like an integer to the database and therefore be tampered with.

This is what I would like to know:

• Why does SQLite behave like this (and maybe other implementations)?
• Can I do something about it? (Without the double quoting?)

---

Just for reference, inserting the string '+test' works as expected:

sqlite> delete from test;
sqlite> insert into test values ('+t');
sqlite> select * from test;
+t

(answer without quotes – whiii!)

Answer 1

This is related to SQLite’s dynamic data typing. In particular, STRING is not a valid type, so SQLite defaults it to NUMERIC affinity. In fact, to quote from that page:

Note that a declared type of “FLOATING POINT” would give INTEGER
affinity, not REAL affinity, due to the “INT” at the end of “POINT”.
And the declared type of “STRING” has an affinity of NUMERIC, not
TEXT.

You want to declare your column as TEXT, not STRING. That will fix it.