sql - MySQL Join Condition -

-

I'm having trouble in thinking in a way to get into MySQL I'm not sure who's for this job It would be most appropriate to include, so when someone tells it, I will edit the title. Here's the essence of what I am trying to do.

I have two tables, call a code , and other sign
These are setup as follows,

student

only the ID field is unique 

 .---- + --------- -------- + ---- ---- + --------. | ID | Name | Parents Mark | + ---- + ----------------- + -------- + -------- + | 1 | Name goes here 1. 0 | 0 | | 2 | Name goes here 2 | 0 | 20 | | 3 | Name goes here 3 | 2 | 45 | 4 | Name goes here 4 | 2 | 50 | | 5 | Name goes here 3 | 1 | 20 | | 6 | Name goes here 1. 0 | 65 | .---- + ----------------- + -------- + --------.

symbol

the id and the name are unique 

 .---- + ----------------- + --------. | ID | Name | Ranking | + ---- + ----------------- + -------- + | 1 | Name goes here 1. 20 | | 2 | Name goes here 2 | 60 | | 3 | Name goes here 3 | 90 | | 4 | Name goes here 4 | 200 | | 5 | Name goes here 5 | 45 | 6 | Name goes here 6. 76 | .---- + ----------------- + --------.

Now, what I want is as follows.
1. I need to join the student on myself so that student parent = student . ID
2. In the above example, I want to select only the line where student Icon (S2) that is the most under parent. In addition, only if student . Join Mark > = 20 (also S2)
3. I want to join the last student . name on symbol . Name (from S1), select the ranking.

Result 

 .---- + ----------------- + -------- + - - ----- + -------- + ---------- | ID | Name | Parents Children Mark | Ranking | + ---- + ----------------- + -------- + -------- + -------- + ---------- + | 1 | Name goes here 1. 0 | 5 | 20 | 20 | | 2 | Name goes here 2 | 0 | 4 | 50 | 60 | .---- + ----------------- + -------- + -------- + -------- + ----------

I think (?) It is possible to use a query, but not sure I

This query should do what you want. 

  SELECT S1.Id, s1.Name, s1.Parent, s2.Id as hair, max (s2.mark) as mark, m. Ranking S1 Inner Join Student S2 On (s1.id = s2.parent and s2.Mark & ​​Gt; = 20) by the students join the left (s1.name = m.name) group on s1.Id, s1 .Name, s1.Parent, Child, Ranking;

Comments

Post a Comment

Popular posts from this blog

c# - ListView onScroll event -

-
I am programming a simple C # application, and I need a Scallow event on the list view. So I inherited the original ListView class created in ListviewEx witch. I found out how to locate the scroll message from WinAPI and I modified the WndProc method. Now I have this WndProc: protected override zero WndProc (Ref message message) {base.WndProc (Ref I); If (m.msg == WM_VSCROLL) {onScroll (This, New EventArgs ()); }} But the problem is, I do not know how to know about scrolling information. This data should be in wParam, but there is a LOWORD macro ++ like in C in C # and I switch to find the criteria like SB_ below, SB_ENDSCROLL, SB_PAGEUP etc. there any way Need to change the LOWORD macro from C #? Or any other way to find the necessary parameters about scrolling? You can define the WParam constants as the following: Private const int WM_HSCROLL = 0x114; Private Constant WM_VSCROLL = 0x115; Private contact int SBHOZZ = 0; Private Consultant SB_VERT = 1; Private Con...
Read more

PHP - get image from byte array -

-
I am trying to create a back-end for my mobile application. I am sending the content of an image in the body of the HTTP request (output stream) as a byte array, I want to read this stream of bytes in PHP scripts and take back an image. Can anyone tell me how can I do this? Thank you. You can obtain the request body $ body = Reading from file_get_contents ('php: // input'); What you do with that data Depending on you, you can write the data in a file as you mentioned that this is image data, you can drop the data into the object can do. Another option is to use and load the image.
Read more

Linux Terminal Problem with Non-Canonical Terminal I/O app -

-
I have a small app written in C to run on Linux. Part of the app accepts user-input from keyboard , And it uses non-canonical terminal mode so that it can respond to each keystroke. The section of the code that accepts input is a simple task that is called repeatedly in the loop: char get_input () {char C = 0; Int res = reading (input_tamille, & amp; c, 1); If (RSS == 0) 0 returns; If (res == -1) {/ * snip error handling * /} return c; } It reads a letter from the terminal if there is no input within a given time limit, (c_cc [VTIME] value in the vocabulary structure), read () 0 And get_input () is called again It all works very well, I have recently discovered that if you run this app in a terminal window, and then the app Close the terminal window without ending, the app will not exit Received, but CPU intensive launches into an infinite loop, where the read () returns 0 without waiting continued. So how can I get out of the apple if it runs from the terminal win...
Read more