optimization - Does mysql query cache the dynamically calculated columns -


i have mysql query:

select my_table.* soundex(my_col)='whatever' or substr(soundex(my_col),4)='whatever' order substr(soundex(my_col),4)='whatever',soundex(my_col)='whatever'

how many times substring function , soundex functions called? mean same inputs mysql cache results on span of 1 query?

if not, how can make change in query each function called minimum times possible.

mysql call function 4 times every returned row, avoid can use subquery, instead of 

  select *    song  order  substr(pre_calculated_soundex, 1, 1) =                      substr(soundex("aaaa"), 1, 1)                                                   + substr(pre_calculated_soundex                      , 2, 1) =                      substr                      (soundex("aaaa"), 2, 1)                      + substr(pre_calculated_soundex, 3, 1)                      = substr(soundex("aaaa"), 3, 1)                        + substr(pre_calculated_soundex, 4, 1                        )                        = substr(soundex("aaaa"), 4, 1)

you can 

select *  (select *, soundex("aaaa") current_soundex song) order               substr(pre_calculated_soundex, 1, 1) = substr(current_soundex , 1, 1)            + substr(pre_calculated_soundex, 2, 1) = substr(current_soundex , 2, 1)            + substr(pre_calculated_soundex, 3, 1) = substr(current_soundex , 3, 1)            + substr(pre_calculated_soundex, 4, 1) = substr(current_soundex , 4, 1)

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