Mysql is a good table: a table with more than one index?

Question

Excuse me,

I have this mini-table with 3 columns, but I will list the values ​​with either one or the other column.

1) Is it good to have two columns with indexes?

2) Should there be only one index for a table?

3) At the limit, if we have a table with 100 columns, for example, and we have 50 of them with indexes, is this normal?

Thanks MEM

Answer 1

Good to have many indexes, even multiple indexes in the same table, if you use them.

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Answer 2

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Answer 3

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