Blank/Zero cell need info copied from a certain cell to corresponding one

[mckeamic]

So I have a spreadsheet doing several things, but here is what I'm stuck on. In column H {min #} if it is blank (or I can have the person put a 0), I need it to copy the number that is in the corresponding cell from column J {max #}.
So say for row 7 american white pelican it is blank {min #} H7, I need it to copy the number that is inputed in to {max #} J7, so it will have min # of 30 and max # of 30.
Where/how would I put the formula?
If it has a number inputted into column H, I don't need it to do anything.
Columns C,E,G,I are blank and just using as a spacer between columns.
Let me know if that is confusing or if anyone has any suggestions.
Thanks

[TABLE="width: 523"]
<tbody>[TR]
[TD]A
[/TD]
[TD]B
[/TD]
[TD]C
[/TD]
[TD] D
[/TD]
[TD]E
[/TD]
[TD] F
[/TD]
[TD] G
[/TD]
[TD] H
[/TD]
[TD]I
[/TD]
[TD] J
[/TD]
[/TR]
[TR]
[TD]3
[/TD]
[TD]species
[/TD]
[TD][/TD]
[TD] temp
[/TD]
[TD][/TD]
[TD] humidity
[/TD]
[TD][/TD]
[TD] min#
[/TD]
[TD][/TD]
[TD] max #
[/TD]
[/TR]
[TR]
[TD]4
[/TD]
[TD]--[/TD]
[TD][/TD]
[TD] --[/TD]
[TD][/TD]
[TD] -- [/TD]
[TD][/TD]
[TD] --[/TD]
[TD][/TD]
[TD] --[/TD]
[/TR]
[TR]
[TD]5
[/TD]
[TD]abdim stork
[/TD]
[TD][/TD]
[TD] 37.2
[/TD]
[TD][/TD]
[TD] 58
[/TD]
[TD][/TD]
[TD] 30
[/TD]
[TD]-
[/TD]
[TD] 33
[/TD]
[/TR]
[TR]
[TD]6
[/TD]
[TD]american goldeneye
[/TD]
[TD] [/TD]
[TD] 37.2
[/TD]
[TD][/TD]
[TD] 10
[/TD]
[TD][/TD]
[TD] 20
[/TD]
[TD]-
[/TD]
[TD] 30
[/TD]
[/TR]
[TR]
[TD]7[/TD]
[TD]american white pelican
[/TD]
[TD] [/TD]
[TD] 37
[/TD]
[TD][/TD]
[TD] 60
[/TD]
[TD][/TD]
[TD]
[/TD]
[TD]-
[/TD]
[TD] 30
[/TD]
[/TR]
[TR]
[TD]8
[/TD]
[TD]australian shelduck
[/TD]
[TD][/TD]
[TD] 37.2
[/TD]
[TD][/TD]
[TD] 10
[/TD]
[TD][/TD]
[TD]
[/TD]
[TD]-
[/TD]
[TD] 33
[/TD]
[/TR]
[TR]
[TD]9
[/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD]-
[/TD]
[TD][/TD]
[/TR]
</tbody>[/TABLE]

 

[Special-K99]

For a formula solution:

A cell can contain a value or a formula, not both.
So if you have column H with preset values then you need to have another column, lets say K.

in K3
=IF(OR(H3<>"",H3=0),J3,H3)

Then use column K instead of column H since column K will now have values that are missing on column H.

QUESTION: Row there is NEITHER a value for H nor J, so what result do you want from that?