> In C there are local variables, where you can save result of impure
> functions when it is important. There are no local variables in SQL
> - with even more extreme example shown in E.Pasma message nearby -
> `SELECT strftime('%f') AS q FROM t WHERE q <> q`;
> oh, by the way, `SELECT CURRENT_TIME AS q FROM t WHERE q <> q`
> trigger that bug too, I've just checked (and it took less than 2
> seconds to trigger).
That is version specific. What version of SQLite are you using? The current
version optimizes out the clause q <> q thusly:
sqlite> .explain
sqlite> explain select value, current_time as q from x where q <> q and value <
1000000000;
SELECT item[0] = {0:0}
item[1] = FUNCTION:current_time() AS q
FROM {0,*} = x
WHERE AND(REGISTER(1),LT({0:0},REGISTER(4)))
END
addr opcode p1 p2 p3 p4 p5 comment
---- ------------- ---- ---- ---- ------------- -- -------------
0 Trace 0 0 0 00
1 Function 0 0 2 current_time(0) 00
2 Function 0 0 3 current_time(0) 00
3 Ne 3 1 2 72
4 Integer 1000000000 4 0 00
5 Goto 0 18 0 00
6 VOpen 0 0 0 vtab:6E06F0:50B800 00
7 Copy 4 7 0 00
8 Integer 4 5 0 00
9 Integer 1 6 0 00
10 VFilter 0 16 5 00
11 IfNot 1 15 1 00
12 VColumn 0 0 8 00
13 Function 0 0 9 current_time(0) 00
14 ResultRow 8 2 0 00
15 VNext 0 11 0 00
16 Close 0 0 0 00
17 Halt 0 0 0 00
18 Transaction 0 0 0 00
19 VerifyCookie 0 1 0 00
20 Goto 0 6 0 00
So you will either get all rows or none.
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