Khmer character map
Every Khmer character, one click from your clipboard, with its code point.
The characters no keyboard puts within reach
The independent vowels, the two consonants that appear only in Pali and Sanskrit, the lek attak numerals, the signs that turn up only in formal writing, and the riel sign itself. All of them are needed occasionally and none of them is on a normal layout.
So people copy them out of a Wikipedia article or a PDF, which is how the wrong code point ends up in a database — several Khmer characters have look-alikes that render identically and sort differently.
A subscript is two characters
It is an invisible marker, U+17D2, followed by a consonant. The font does the stacking; there is no single "subscript ka" character to copy. Take only the visible half from somewhere else and you have half a subscript, which looks nearly right and is a different string.
The subscripts here are copied as both characters together, which is why they paste correctly and a character grabbed from a web page often does not.
Khmer digits are not styled Arabic ones
០ through ៩ are their own code points. A phone number typed in Khmer digits will never match the same number typed in Arabic digits, however identical they look to a reader, because to a computer they share nothing at all.
That is worth deciding once for any form or database: accept both, store one. The Khmer Unicode checker on this site will tell you when a piece of text has ended up with a mixture.
When something misbehaves, read the code point
A character that renders oddly, sorts strangely or refuses to match is almost always a different character to the one it appears to be. The glyph will not tell you; the code point will.
Paste anything into the box at the top of this page and it will show you exactly which characters you have, in order. That is usually the whole diagnosis.