How can I add new array elements at the beginning of an array in Javascript?

Source: https://stackoverflow.com/questions/8073673/how-can-i-add-new-array-elements-at-the-beginning-of-an-array-in-javascript

Use unshift. It's like push, except it adds elements to the beginning of the array instead of the end.

• unshift/push - add an element to the beginning/end of an array
• shift/pop - remove and return the first/last element of and array

A simple diagram...

   unshift -> array <- push
   shift   <- array -> pop

and chart:

          add  remove  start  end
   push    X                   X
    pop           X            X
unshift    X             X
  shift           X      X

Check out the MDN Array documentation. Virtually every language that has the ability to push/pop elements from an array will also have the ability to unshift/shift (sometimes called push_front/pop_front) elements, you should never have to implement these yourself.

Windows Firewall, Tinywall and GIT

Source: https://stackoverflow.com/questions/23965340/windows-firewall-tinywall-and-git

To get TinyWall to work with git over SSH, you must white-list:

sh.exe
git.exe
ssh.exe

To work with git over HTTPS, you need only whitelist:

C:\Program Files (x86)\Git\libexec\git-core\git-remote-https.exe

or

C:\Program Files\Git\mingw64\libexec\git-core\git-remote-https.exe

What is the difference between “INNER JOIN” and “OUTER JOIN”?

Source: https://stackoverflow.com

INNER JOIN gets all records that are common between both tables based on the foreign key

LEFT JOIN gets all records from the LEFT linked table but if you have selected some columns from the RIGHT table, if there is no related records, these columns will contain NULL

RIGHT JOIN is like the above but gets all records in the RIGHT table

FULL JOIN gets all records from both tables and puts NULL in the columns where related records do not exist in the opposite table

Assuming you're joining on columns with no duplicates, which is a very common case:

• An inner join of A and B gives the result of A intersect B, i.e. the inner part of a Venn diagramintersection.
• An outer join of A and B gives the results of A union B, i.e. the outer parts of a Venn diagram union.

Examples

Suppose you have two tables, with a single column each, and data as follows:

A    B
-    -
1    3
2    4
3    5
4    6

Note that (1,2) are unique to A, (3,4) are common, and (5,6) are unique to B.

Inner join

An inner join using either of the equivalent queries gives the intersection of the two tables, i.e. the two rows they have in common.

select * from a INNER JOIN b on a.a = b.b;
select a.*, b.*  from a,b where a.a = b.b;

a | b
--+--
3 | 3
4 | 4

Left outer join

A left outer join will give all rows in A, plus any common rows in B.

select * from a LEFT OUTER JOIN b on a.a = b.b;
select a.*, b.*  from a,b where a.a = b.b(+);

a |  b
--+-----
1 | null
2 | null
3 |    3
4 |    4

Right outer join

A right outer join will give all rows in B, plus any common rows in A.

select * from a RIGHT OUTER JOIN b on a.a = b.b;
select a.*, b.*  from a,b where a.a(+) = b.b;

a    |  b
-----+----
3    |  3
4    |  4
null |  5
null |  6

Full outer join

A full outer join will give you the union of A and B, i.e. all the rows in A and all the rows in B. If something in A doesn't have a corresponding datum in B, then the B portion is null, and vice versa.

select * from a FULL OUTER JOIN b on a.a = b.b;

 a   |  b
-----+-----
   1 | null
   2 | null
   3 |    3
   4 |    4
null |    6
null |    5