sql - Select a value that has a greater number of values -

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let's have table one:

     table t:         b      -------    1  x | o    2  x | o    3  x | p    4  y | o    5  y | p    6  y | p    7  z | o    8  z | o    9  z | p

i want select values in column have greater number of values in column b.

for example, want select x, y, or z if have more o's p's.

i've made several attempts, can't figure out how this.

so, how can write query retrieve want?

edit: expected output be:

    - 1 x 2 z

this sounds aggregation. this:

select t group having sum(b = 'o') > sum(b = 'p');

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