MySQL equivalent Oracle Lag, Partition By - Query Help

[Si Han Tang]

I need to retrieve invoices from 3 tables.
Table Project_Detail has my project details
Table Project_Item storing items for my project. each project have 1 or more items.
Table Project_Item_Invoice will store invoices for each items in each project. 1 item may have more than 1 invoice also.

Query:
SELECT A.Project_No, B.Item_ID, B.Item_Name,
C.Invoice_ID, C.Date, C.Amount, C.Invoice_No
FROM Project_Detail A
LEFT JOIN Project_Item B ON A.Project_No = B.Project_No
LEFT JOIN Project_Item_Invoice C ON A.Project_No = C.Project_No AND
B.Item_ID = C.Item_ID
WHERE A.Project_No LIKE 'WPJ%' AND A.Project_Status = 'Closed'
ORDER BY A.Project_No DESC, B.Item_ID, C.Invoice_ID

The selected data from database:
___________________________________________________________________________
|Project_No | Item_ID | Item_Name | Invoice_ID | Date | Amount | Invoice_No |
---------------------------------------------------------------------------
|WPJ-0906-1693 | 1 | TNA0052941 | 1 | 2009-08-25 | 1207.58 | 0907-1141 |
|WPJ-0906-1693 | 1 | TNA0052941 | 2 | 2009-08-26 | 2836.70 | 0906-1153 |
|WPJ-0906-1693 | 1 | TNA0052941 | 3 | 2009-08-27 | 1234.70 | 0906-1157 |
|WPJ-0906-1693 | 2 | TNA0052942 | 1 | 2009-08-26 | 5678.90 | 0906-1150 |
|WPJ-0906-1693 | 2 | TNA0052942 | 2 | 2009-08-27 | 4356.20 | 0906-1158 |

The result I want is like this:
___________________________________________________________________________
|Project_No | Item_ID | Item_Name | Invoice_ID | Date | Amount | Invoice_No |
---------------------------------------------------------------------------
|WPJ-0906-1693 | 1 | TNA0052941 | 1 | 2009-08-25 | 1207.58 | 0907-1141 |
|___(blank)____ | _ | __(blank)___ | 2 | 2009-08-26 | 2836.70 | 0906-1153 |
|___(blank)____ | _ | __(blank)___ | 3 | 2009-08-27 | 1234.70 | 0906-1157 |
|___(blank)____ | 2 | TNA0052942 | 1 | 2009-08-23 | 5678.90 | 0906-1150 |
|___(blank)____ | _ | __(blank)___ | 2 | 2009-08-25 | 4356.20 | 0906-1158 |

In Oracle, I can select the data with decode, lag, partition by:

select
decode (t.Project_No,t.Prev_Project_No,'') Project_No,
decode (t.Item_ID,t.Prev_Item_Id,'') Item_Id,
decode (t.Item_Name,t.Prev_Item_Name,'') Item_Name,
t.Invoice_ID, t.Date, t.Amount, t.Invoice_No
from
(
SELECT
A.Project_No, B.Item_ID, B.Item_Name,
C.Invoice_ID, C.Date, C.Amount, C.Invoice_No,
lag(A.Project_No,1,0)
over (partition by A.Project_No
order by A.Project_No DESC, B.Item_ID, C.Item_Name )Prev_Project_No,
lag(B.Item_ID,1,0)
over (partition by B.Item_ID
order by A.Project_No DESC, B.Item_ID, C.Item_Name )Prev_Item_Id,
lag(B.Item_Name,1,0)
over (partition by C.Item_Name
order by A.Project_No DESC, B.Item_ID, C.Item_Name )Prev_Item_Name,
FROM Project_Detail A
LEFT JOIN Project_Item B ON A.Project_No = B.Project_No
LEFT JOIN Project_Item_Invoice C ON A.Project_No = C.Project_No
AND B.Item_ID = C.Item_ID
WHERE A.Project_No LIKE 'WPJ%' AND A.Project_Status = 'Closed'
) t

How to do this in MySQL? I only know MySQL have 'if' (equal to 'decode' in Oracle) statement. How about lag and partition?