When an ionic compound dissolves in water and becomes ions.
1) Typically we see:
$\ce{AB ->}$ Ions $\ce{A+ + B-}$
$\ce{ABC ->}$ Ions $\ce{AB+ + C-}$
2) But how about the one below, is there any case that will fit the situation
$\ce{ABC2 -> A+ + B+ + 2C-}$
or $\ce{AB2C-> A+ + 2B+ + C^3-}$
Yup, they are definitely possible. Such salts are called as mixed salts. They furnish more than two ions when dissolved in water. A popular example is Mohr's salt, popularly used as a standard titrant to measure concentrations of oxidizing agents. It's (anhydrous) formula is:
$$\ce{Fe^{II}(NH4)2(SO4)2}$$
This salt on dissolving in water would split as:
$$\ce{Fe^{II}(NH4)2(SO4)2 <=>> Fe^2+ + 2NH4+ + 2SO4^2-}$$
This is one such example. There are many others, notably alums. Alums are a general type of mixed salts, of the form:
$$\ce{A^{I}M^{III}(SO4)2}$$
where $\ce{A^{I}}$ is a monovalent metal ion, and $\ce{M^{III}}$ is a trivalent metal ion. Clearly, these are also mixed salts.
These are just a few practical examples. There's literally quite nothing that can stop imagination of course.
Another is the de-icing compound calcium magnesium acetate, $\ce{CaMg2(C2H3O2)6}$ (https://en.m.wikipedia.org/wiki/Calcium_magnesium_acetate). Like all such "double cation salts", this compound has a crystal structure with two different sites for cations; in this case one kind of site has the calcium ions and the other has the magnesium ions. This combination enables a reproducible stoichiometry, but when the crystal structure is broken down by dissolving the salt you just have "ion soup".
