two simple and short solution using function "TRIM" or "XOR"
using function "TRIM":\n\n update salary set sex = TRIM(sex from "fm");\n\n 2. using the bit op "XOR":\n \n update salary set sex = char(11 ^ ascii(sex));\n\n t
1. using function "TRIM":\n```\n update salary set sex = TRIM(sex from "fm");\n ```\n 2. using the bit op "XOR":\n ```\n update salary set sex = char(11 ^ ascii(sex));\n ```\n the `11` in the statement  is the result of  `102 ^ 109` where `102` stands for `"f"` in ascii and `109` for `"m"`.\n
[]