Using JSON type to realize array function in MySQL

mysql There are no arrays in , Sometimes it's inconvenient , You can use JSON Type data implements a class array function .

1、 Array generation

Only schematic codes are posted

...
delimiter $$
drop procedure if exists sp_JSArr;
create procedure  sp_JSArr(out jsArr json )  
begin

declare retJson json default "[]" ;
set retJson= json_array_append (retJson ,"$",json_object("val",1));
set retJson= json_array_append (retJson ,"$",json_object("val",2));
set	jsArr = retJson;
end $$
delimiter ;

...

2、 Usage method

  	--  Returns an array of 
	call sp_JSArr(jsArr );

	if JSON_VALID(jsArr ) then 
	-- @i  Subscript variables for arrays 
		set @i=0;
		set @ArrLen = JSON_LENGTH(jsArr );
     
		loop_PkArr:loop --  Loop start 
			if @i>=@ArrLen then 
				leave loop_PkArr;  --
			end if;
			--  How to use similar arrays 
			set @jsInex = concat("$[",i,"].val");
			set @val= json_extract(jsArr ,@jsIndex) ;
			
            set @i=@i+1;
		end loop;
   
    end if ;

MaraSun 2022-07-26 BJFWDQ
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