如何在数据库中随机字母列表的每个字母后添加逗号

Question

如果我的所有记录都有随机字母，我如何在每个字母后添加逗号？

我有什么：

1. AHGJTOSIYGJ
2. OTPDBSKGY
3. HFRYEC
4. OPFKWIFS
// etc

我需要什么：

1. A, H, G, J, T, O, S, I, Y, G, J,
2. O, T, P, D, B, S, K, G, Y,
3. H, F, R, Y, E, C,
4. O, P, F, K, W, I, F, S,
// etc

Answer 1

我们需要从 1 到最大长度输入字符串的序列号工作表：

create table seqnum(X int not null, primary key(X));
insert into seqnum values(1),(2),(3),(4);
insert into seqnum select X+4 from seqnum;
insert into seqnum select X+8 from seqnum;
insert into seqnum select X+16 from seqnum;
insert into seqnum select X+32 from seqnum;

测试表：

create table test6(id int, lett varchar(100));
insert into test6 values(1,'AHGJTOSIYGJ'),(2,'OTPDBSKGY'),(3,'HFRYEC'),(4,'OPFKWIFS');

查询以选择表 test6 上更改的字母：

select id, lett, group_concat(substr(lett,S.X,1) ORDER BY T.id, S.x SEPARATOR ', ')
  from test6 T, seqnum S
 where S.X<=length(T.lett)
 group by id

结果：

1 | AHGJTOSIYGJ | A, H, G, J, T, O, S, I, Y, G, J
2 | OTPDBSKGY   | O, T, P, D, B, S, K, G, Y
3 | HFRYEC      | H, F, R, Y, E, C
4 | OPFKWIFS    | O, P, F, K, W, I, F, S

对于现有表的更新值使用查询：

update test6 A
  join (
        select id, group_concat(substr(lett,S.X,1) ORDER BY T.id, S.x SEPARATOR ', ') new
          from test6 T, seqnum S
         where S.X>0 and S.X<=length(T.lett)
         group by id
       ) B ON A.id=B.id
   set A.lett=B.new

Test on sqlfiddle.com

Answer 2

这些操作应该通过应用程序级别而不是数据库来完成。但是，您真的想从数据库级别执行此操作，您可以使用用户定义的函数轻松执行此操作。这是执行此操作的函数

delimiter //

create function myFunction(myString varchar(255)) 
returns varchar(255)
begin
 declare strLen int ;
 declare lookupChar char(1);
 declare finalString varchar(255);
 declare x int;

 set strLen = length(myString);
 set x = 1 ;
 set finalString = '';
 while x <= strLen do
   set lookupChar = substring(myString,x,1);
   if finalString = '' then 
     set finalString = lookupChar;
   else 
     set finalString = concat(finalString,',',lookupChar);
   end if;
   set x = x+1;
 end while;
 return finalString;
end//

delimiter;

让我们在 mysql 上运行它

mysql> create table mytable (id int, value varchar(100));
Query OK, 0 rows affected (0.19 sec)

mysql> insert into mytable values (1,'AHGJTOSIYGJ'),(2,'OTPDBSKGY'),(3,'HFRYEC'),(4,'OPFKWIFS');
Query OK, 4 rows affected (0.02 sec)

mysql> select * from mytable ;
+------+-------------+
| id   | value       |
+------+-------------+
|    1 | AHGJTOSIYGJ |
|    2 | OTPDBSKGY   |
|    3 | HFRYEC      |
|    4 | OPFKWIFS    |
+------+-------------+
4 rows in set (0.00 sec)

现在让我们创建函数

mysql> delimiter //
mysql> create function myFunction(myString varchar(255)) 
    -> returns varchar(255)
    -> begin
    ->  declare strLen int ;
    ->  declare lookupChar char(1);
    ->  declare finalString varchar(255);
    ->  declare x int;
    -> 
    ->  set strLen = length(myString);
    ->  set x = 1 ;
    ->  set finalString = '';
    ->  while x <= strLen do
    ->    set lookupChar = substring(myString,x,1);
    ->    if finalString = '' then 
    ->      set finalString = lookupChar;
    ->    else 
    ->      set finalString = concat(finalString,',',lookupChar);
    ->    end if;
    ->    set x = x+1;
    ->  end while;
    ->  return finalString;
    -> end//
Query OK, 0 rows affected (0.00 sec)

mysql> delimiter ;

到目前为止一切顺利，现在让我们使用函数选择值

mysql> select id,myFunction(value) as value from mytable ;
+------+-----------------------+
| id   | value                 |
+------+-----------------------+
|    1 | A,H,G,J,T,O,S,I,Y,G,J |
|    2 | O,T,P,D,B,S,K,G,Y     |
|    3 | H,F,R,Y,E,C           |
|    4 | O,P,F,K,W,I,F,S       |
+------+-----------------------+

您可以对整个表格执行此操作，也可以在需要时轻松进行更新。