我有三张桌子
1) tax_master
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| tax_id ||tax_name||tax_value|
--------------------------------
| 1 || VAT || 5 |
--------------------------------
| 2 || LBT || 8 |
-------------------------------
2) item_master
----------------------
| item_id ||price |
----------------------
| 1 || 30 |
----------------------
| 2 || 100 |
----------------------
3) item_tax
-----------------------------------
| item_tax_id ||item_tax||item_id|
-----------------------------------
| 1 || 1 || 1 |
-----------------------------------
| 2 || 2 || 2 |
-----------------------------------
| 2 || 2 || 1 |
-----------------------------------
所以现在我想要这样的输出
----------------------------------
| item_id || VAT || LBT |
----------------------------------
| 1 || 1.5 || 2.4 |
----------------------------------
| 2 || - || 1.6 |
----------------------------------
增值税的值计算为 5/100*30 为 5% on 30=1.5 所以想要这样的输出我很困惑。并尝试了很多但力不从心。你能帮帮我吗