Improved some db queries.

Speedups (on live server):

* add
	- 3.5~4 times
* eventmgr
	- 35~45 times

To test:
 1. Get the files
    - https://gist.github.com/Prillan/01124ebeca39de0ad61b
    - https://gist.github.com/Prillan/8d33615dc40302384af7
    - https://gist.github.com/Prillan/34e47a00d40b6eb6fad9
    - https://gist.github.com/Prillan/5f3476dbf8be2082fcfd
    - https://gist.github.com/Prillan/55c00eaad43da07a89e7
 2. Put them in `/tmp`
 3. Run `./test.sh`

You should see output like this:
````
--- Testing add.noopt.sql (#1)---

real    0m4.357s
user    0m0.030s
sys     0m0.017s
------------------
--- Testing add.opt.sql (#1)---

real    0m1.839s
user    0m0.027s
sys     0m0.017s
------------------
Same results
--- Testing add.noopt.sql (#2)---

real    0m4.333s
user    0m0.030s
sys     0m0.014s
------------------
--- Testing add.opt.sql (#2)---

real    0m1.221s
user    0m0.026s
sys     0m0.018s
------------------
Same results
--- Testing eventmgr.noopt.sql (#1)---

real    0m5.457s
user    0m0.052s
sys     0m0.008s
------------------
--- Testing eventmgr.opt.sql (#1)---

real    0m0.159s
user    0m0.046s
sys     0m0.014s
------------------
Same results
--- Testing eventmgr.noopt.sql (#2)---

real    0m6.072s
user    0m0.051s
sys     0m0.010s
------------------
--- Testing eventmgr.opt.sql (#2)---

real    0m0.136s
user    0m0.049s
sys     0m0.013s
------------------
Same results

````