Example of if-else Statement (VHDL) - 2023.2 English

library IEEE;
use IEEE.std_logic_1164.all;

entity mux4 is port (
a, b, c, d : in std_logic_vector (7 downto 0);
sel1, sel2 : in std_logic;
outmux : out std_logic_vector (7 downto 0));
end mux4;

architecture behavior of mux4 is begin
process (a, b, c, d, sel1, sel2)
begin
if (sel1 = '1') then
if (sel2 = '1') then
outmux <= a;

else outmux <= b;
else
end if;
if (sel2 = '1') then outmux <= c;
else
outmux <= d;
end if;
end if;
end process;
end behavior;