How does a Recursive CTE run, line by line?

Question

I think I\'ve got the format of Recursive CTEs down well enough to write one, but still find myself frustrated to no end that I cannot manually process one (pretend to be th

Answer 1

Step 1:

1 Europe NULL Europe
2 Asia   NULL Asia

Step 2:

1 Europe  NULL Europe
2 Asia    NULL Asia
3 Germany 1    Europe/Germany
4 UK      1    Europe/UK
5 China   2    Asia/China
6 India   2    Asia/India

Step 3:

1 Europe   NULL Europe
2 Asia     NULL Asia
3 Germany  1    Europe/Germany
4 UK       1    Europe/UK
5 China    2    Asia/China
6 India    2    Asia/India
7 Scotland 4    Europe/UK/Scotland

Step 4:

1 Europe    NULL Europe
2 Asia      NULL Asia
3 Germany   1    Europe/Germany
4 UK        1    Europe/UK
5 China     2    Asia/China
6 India     2    Asia/India
7 Scotland  4    Europe/UK/Scotland
8 Edinburgh 7    Europe/UK/Scotland/Edinburgh

Step 5:

1 Europe    NULL Europe                             0
2 Asia      NULL Asia                               0
3 Germany   1    Europe/Germany                     1
4 UK        1    Europe/UK                          1
5 China     2    Asia/China                         1
6 India     2    Asia/India                         1
7 Scotland  4    Europe/UK/Scotland                 2
8 Edinburgh 7    Europe/UK/Scotland/Edinburgh       3
9 Leith     8    Europe/UK/Scotland/Edinburgh/Leith 4

The last column in step 5 is the Level. During each level the rows get added with respect to what is already available. Hope this helps.