EXCEL unique values from multiple seperated columns into one column

Question

Table 1  table 2  table 3
a                 a
e                 a
d                 g
t                 d
e                 c
e                 c

I want to have a results

Table 7
a
c
d
t
g
e

but theses two table is not next to each other... Thanks,

Answer 1

TEXTJOIN() and FILTERXML() can do it. Try-

=FILTERXML("<t><s>"&TEXTJOIN("</s><s>",TRUE,A2:C7)&"</s></t>","//s[not(preceding::*=.)]")

Answer 2

Using VTSACK() Function,

Formula used in cell E2

=UNIQUE(VSTACK(A2:A7,C2:C7))

Please note VSTACK() Function currently available in O365 Insiders Beta Channel Version, arrays can be non-contiguous irregular but needs to be vertical.

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Also since you have non-contiguous ranges, TEXTJOIN() can also perform the same by wrapping it within FILTERXML() Function.

Formula used in cell F2

=UNIQUE(FILTERXML("<t><s>"&TEXTJOIN("</s><s>",,A2:A7,C2:C7)&"</s></t>","//s"))

Note: Since you have not mentioned your Excel Version, assumption made that you are using O365 - updated version.