| email           | result  |
----------------------------
| abc@gmail.com   |0.12      |
| dsv@gmail.com   |0.23      |
| rthgmail.com    | 0.45     |
| hfg@gmail.com   |0.56      |
| yyt@gmail.com   | 0.78     |
| hjg@gmail.com   | 0.35     |

| resource        |
 -------------------
 | 0.5             |

| temp            |
-------------------
|NULL             |

UPDATE table3 SET temp = table1.result + table2.resource WHERE email = 'abc@gmail.com'