Question

我有一个带有文本的列，按ASCII排序，应按以下顺序排序：

library ieee;
  use ieee.std_logic_1164.all;
  use ieee.numeric_std.all;

entity mem_control is 
    port(
  clk              : in    std_logic;
  write_en         : in    std_logic;
  read_en          : in    std_logic;
  bus_address      : in    std_logic_vector(11 downto 0);
  bus_data         : inout std_logic_vector(31 downto 0);
  write_en_sram    : out   std_logic;
  read_en_led      : out   std_logic;
  write_en_led     : out   std_logic;
  write_en_scratch : out   std_logic;
  bus_in_sram      : in    std_logic_vector(31 downto 0);
  bus_out_sram     : out   std_logic_vector(31 downto 0);
  bus_in_led       : in    std_logic_vector(31 downto 0);
  bus_out_led      : out   std_logic_vector(31 downto 0);
  bus_in_scratch   : in    std_logic_vector(31 downto 0);
  bus_out_scratch  : out   std_logic_vector(31 downto 0);
  addr_out         : out   std_logic_vector(11 downto 0)
);

end mem_control;

architecture bhv of mem_control is 
--buffer signals
signal bus_out     : std_logic_vector(31 downto 0) := (others => '0');
--processes begin
begin

mem_write : process(clk) is 
  begin
    if rising_edge(clk) then
       if write_en = '1' and read_en ='0' then   --writing logic
         case To_integer(unsigned(bus_address)) is
           when 16#000# to 16#3FF# =>
             write_en_sram <= '1';
             write_en_led <= '0';
             write_en_scratch <= '0';
             bus_out_sram <= bus_data;
             addr_out <= bus_address;
           when 16#400# =>
             write_en_sram <= '0';
             write_en_led <= '1';
             write_en_scratch <= '0';
             bus_out_led <= bus_data;
           when 16#404# =>
             write_en_sram <= '0';
             write_en_led <= '0';
             write_en_scratch <= '1';
             bus_out_scratch <= bus_data;
           when others =>
             null;
           end case;
         end if;
       end if;
end process mem_write;

mem_read : process(clk) is
begin
    if rising_edge(clk) then
       if read_en = '1' and write_en = '0' then  --reading logic

          case To_integer(unsigned(bus_address)) is
             when 16#000# to 16#3FF# =>
               bus_out <= bus_in_sram;
               read_en_led <= '0';
               addr_out <= bus_address;
             when 16#400# =>
               bus_out <= bus_in_led;
               read_en_led <= '1';

             when 16#404# =>
               bus_out <= bus_in_scratch;
               read_en_led <= '0';

             when others =>
               null;
             end case;
          end if;
        end if;
  end process mem_read;

--led register and tristate buffers  
bus_data <= bus_out when(write_en = '0' and read_en = '1') else (others => 'Z');

end bhv;

然而，它被命令为：

-  (hyphen)
0
1  (numbers)
2
A  (uppercase)
B
_  (underscore)
a
b  (lowercase)
c

如何按ASCII值进行排序？

Answer 1

您可以使用ASCII：

SELECT *
FROM tab
ORDER BY ASCII(col_name) ASC

Answer 2

排序顺序由排序规则控制。您可以使用BINARY排序规则按原始字节排序，在ASCII数据的情况下，它将使其按ASCII值排序。见https://dev.mysql.com/doc/refman/5.7/en/sorting-rows.html

SELECT ...
FROM mytable
ORDER BY BINARY mycolumn

这比使用ASCII()函数更灵活，因为该函数只返回第一个字符的ASCII值。使用BINARY排序规则允许按完整字符串排序。

MYSQL - 按ASCII值排序列

2 个答案: