MySQL parsing serialized fields

Sometimes you need to query statistics similar to those in the above table ext Field in the serialized string key The corresponding value is troublesome , Ordinary sql Cannot query directly , You can't add conditions to query ,mysql There is no relevant parsing method , Therefore, it is written as follows mysql Method ：

First write a little demo The beta ：

create function yangstr(str varchar(255), tar varchar(50)) returns varchar(255) no sql begin declare pos int; declare secstr varchar(255); declare finstr varchar(255); set pos = locate(tar,str); if pos = 0 then return null; else set secstr  = substr(str,pos + LENGTH(tar) + 2); set finstr = substr(secstr,locate(':',secstr)+1,locate(';',secstr) - 1 - locate(':',secstr)); set finstr = trim(BOTH '"' FROM finstr); return finstr; end if; end$$

Then I wrote a recursive method to deal with the existence of arrays , however mysql function Recursion is not supported , So it is changed to the following loop processing ：

create function yangstr(str varchar(255), tar varchar(50)) returns varchar(255) no sql begin 
    declare pos int; declare pointpos int; declare secstr varchar(255); declare tartype char(2); declare fircolon int; declare seccolon int; declare finstr varchar(255); declare currtar varchar(50);declare nest boolean default true;
    while nest do
        set pointpos = locate('.',tar);
        if pointpos = 0 then 
            # Basic types 
            set pos = locate(tar,str); 
            if pos = 0 then 
                return null; 
            else 
                set secstr  = substr(str,pos + LENGTH(tar) + 2); 
                set tartype=left(secstr,2); 
                if tartype = 'i:' then 
                    set finstr = substr(secstr,locate(':',secstr)+1,locate(';',secstr) - 1 - locate(':',secstr)); set finstr = trim(BOTH '"' FROM finstr); 
                    return finstr;
                elseif tartype = 's:' then 
                    set fircolon = locate(':',secstr);
                    set finstr = substr(secstr,fircolon+1,locate(';',secstr) - fircolon); 
                    set seccolon = locate(':',finstr);
                    set finstr = substr(finstr,seccolon+1,locate(';',finstr) - 1 - seccolon);
                    set finstr = trim(BOTH '"' FROM finstr);
                    return finstr;
                else
                    set str = secstr;
                end if;
            end if;
        else
            #array
            set currtar = left(tar, pointpos - 1);
            set pos = locate(currtar,str); 
            if pos = 0 then 
                return null; 
            else 
                set str = substr(str,pos + LENGTH(currtar) + 2); 
                set tartype=left(str,2); 
                if tartype = 'a:' then
                    set tar = substr(tar, pointpos + 1);
                end if;
            end if;

        end if;
    end while;
end$$

Of course, this is not true parsing , Just for the purpose of getting the value , Existing in field key The corresponding value exists in the field type to be queried （tartype Value ） There are certain conflict problems , So before using, make sure that there is no relevant string in the field value （ Of course, the possibility of conflict is relatively small ）.

The whole debugging process is still very troublesome , But it pays off , Let's take a look at the implementation effect ：

SELECT `name`,age,yangstr(ext,'credit') FROM my_user ：

SELECT `name`,age,yangstr(ext,'title') FROM my_user ：

 SELECT `name`,age,yangstr(ext,'credit') FROM my_user WHERE yangstr(ext,'credit') > 100

  Basically meet the use needs , If it's helpful for you to study or work , Point a free like , thank you ！