Some tips

[KAKAN]

I have used this 2 editors only:-

Notepad++
TIP, Goto Language in the toolbar, select C, then C++ (or) select S, then select SQL

Sublime Text 3
TIP, On the bottom right cornor, there should be a text named 'plain text', it may differ, click on it, select D from the list

Hope that helps you, if u know more, post here, I'll update this

[Thijn]

Don't use C++ for squirrel. On Sublime Text there's this awesome syntax highlighter called "d"
Just press CTRL + SHIFT + P then type ssd

[KAKAN]

Thanks, tried it. IT's really awesome, UPDATED

[MatheuS]

I like to use the SQL language in Notepad++ to edit.

[rulk]

I just use the standard notepad, the console lets you know about syntax errors.

[KAKAN]

UPDATED!, Thanks @MatheuS for telling me about SQL