将 mysql 字段拆分为多行

Question

I have a table which has a field called "Codes", like this;

The result would be something like this(This is from another db, need the query:!):

Another example:

Note that the pro_ parent_code field is the first @@ of the Code column.

My query:

SELECT 
    SUBSTRING_INDEX(SUBSTRING_INDEX(Codigos, '@@', 1), '@@', 1) AS pro_codigo,
    SUBSTRING_INDEX(SUBSTRING_INDEX(Codigos, '@@', 1), ' ', -1) AS pro_codigo_padre 
FROM table

the result:

Answer 1

Create a function to Split the values

Create FUNCTION [dbo].[Func_Split]
(   
    @String varchar(max),
    @Delimiter char
)
RETURNS @Temp TABLE (Srno int identity, Items varchar(max)) 
AS
begin
    Declare @Index int=1, @Item varchar(max)

    if(Len(@String)<=0 or isnull(@String, '')='')
    begin
        return
    end
    else
    begin
        while @Index>0
        begin
            set @Index = CHARINDEX(@Delimiter, @String)

            if(@Index>0)
            begin
                set @Item = Left(@String, @Index-1)
            end
            else
            begin
                set @Item=@String
            end

            if(Len(@Item)>0)
            begin
                insert into @Temp
                (Items)
                values
                (@Item)
            end

            set @String = RIGHT(@String, Len(@String)-@Index)
            IF len(@String) = 0 BREAK
        end
    end
    Return
end

Modify your query accordingly to use it in your query

Eg

select Items from dbo.Func_Split('XYZ@@123@@456','@@')

Answer 2

Here are two methods.

The first uses recursion.
The second uses a Tally table/query with numbers.

 create table Codes ( id int auto_increment primary key, code varchar(100) ) insert into Codes (code) values ('ADV000001@@TB1234567@@TB8901234@@TB5678901@@')

 with recursive CTE as ( select 1 as n, SUBSTRING_INDEX(SUBSTRING_INDEX(code, '@@', 1), '@@', -1) as child, SUBSTRING_INDEX(SUBSTRING_INDEX(code, '@@', 1), '@@', -1) as parent from Codes union all select n+1, SUBSTRING_INDEX(SUBSTRING_INDEX(code, '@@', n+1), '@@', -1) as child, SUBSTRING_INDEX(SUBSTRING_INDEX(code, '@@', 1), '@@', -1) as parent from Codes join CTE on n < (length(code)-length(replace(code,'@@',','))) ) select child as code, nullif(parent, child) as code_parent from CTE

 code | code_parent:-------- |:---------- ADV000001 |  null TB1234567 |  ADV000001 TB8901234 |  ADV000001 TB5678901 |  ADV000001 

 select SUBSTRING_INDEX(SUBSTRING_INDEX(code, '@@', n), '@@', -1) as child,SUBSTRING_INDEX(SUBSTRING_INDEX(code, '@@', 1), '@@', -1) as parent from Codes join (select 0 as n union select 1 union select 2 union select 3 union select 4 union select 5 union select 6 union select 7 union select 8 union select 9 ) nums on n between 1 and (length(code)-length(replace(code,'@@',',')))

 child | parent:-------- |:-------- ADV000001 | ADV000001 TB1234567 |  ADV000001 TB8901234 |  ADV000001 TB5678901 |  ADV000001 

db<>fiddle here