SQL 분할 값을 여러 행으로

SQL 분할 값을 여러 행으로

---

나는 테이블이있다 :

id | name    
1  | a,b,c    
2  | b

다음과 같은 출력을 원합니다.

id | name    
1  | a    
1  | b    
1  | c    
2  | b

---

1부터 분할 할 최대 필드까지의 숫자를 포함하는 숫자 테이블을 만들 수있는 경우 다음과 같은 솔루션을 사용할 수 있습니다.

select
  tablename.id,
  SUBSTRING_INDEX(SUBSTRING_INDEX(tablename.name, ',', numbers.n), ',', -1) name
from
  numbers inner join tablename
  on CHAR_LENGTH(tablename.name)
     -CHAR_LENGTH(REPLACE(tablename.name, ',', ''))>=numbers.n-1
order by
  id, n

여기에서 바이올린을 참조 하십시오 .

테이블을 만들 수없는 경우 솔루션은 다음과 같습니다.

select
  tablename.id,
  SUBSTRING_INDEX(SUBSTRING_INDEX(tablename.name, ',', numbers.n), ',', -1) name
from
  (select 1 n union all
   select 2 union all select 3 union all
   select 4 union all select 5) numbers INNER JOIN tablename
  on CHAR_LENGTH(tablename.name)
     -CHAR_LENGTH(REPLACE(tablename.name, ',', ''))>=numbers.n-1
order by
  id, n

여기에 예제 바이올린이 있습니다 .

---

여기에서 열 이름이 변경된 참조를 가져 왔습니다.

DELIMITER $$

CREATE FUNCTION strSplit(x VARCHAR(65000), delim VARCHAR(12), pos INTEGER) 
RETURNS VARCHAR(65000)
BEGIN
  DECLARE output VARCHAR(65000);
  SET output = REPLACE(SUBSTRING(SUBSTRING_INDEX(x, delim, pos)
                 , LENGTH(SUBSTRING_INDEX(x, delim, pos - 1)) + 1)
                 , delim
                 , '');
  IF output = '' THEN SET output = null; END IF;
  RETURN output;
END $$


CREATE PROCEDURE BadTableToGoodTable()
BEGIN
  DECLARE i INTEGER;

  SET i = 1;
  REPEAT
    INSERT INTO GoodTable (id, name)
      SELECT id, strSplit(name, ',', i) FROM BadTable
      WHERE strSplit(name, ',', i) IS NOT NULL;
    SET i = i + 1;
    UNTIL ROW_COUNT() = 0
  END REPEAT;
END $$

DELIMITER ;

---

내 변형 : 테이블 이름, 필드 이름 및 구분 기호를 인수로 사용하는 저장 프로 시저. 게시물 http://www.marcogoncalves.com/2011/03/mysql-split-column-string-into-rows/에서 영감을 얻었습니다 .

delimiter $$

DROP PROCEDURE IF EXISTS split_value_into_multiple_rows $$
CREATE PROCEDURE split_value_into_multiple_rows(tablename VARCHAR(20),
    id_column VARCHAR(20), value_column VARCHAR(20), delim CHAR(1))
  BEGIN
    DECLARE id INT DEFAULT 0;
    DECLARE value VARCHAR(255);
    DECLARE occurrences INT DEFAULT 0;
    DECLARE i INT DEFAULT 0;
    DECLARE splitted_value VARCHAR(255);
    DECLARE done INT DEFAULT 0;
    DECLARE cur CURSOR FOR SELECT tmp_table1.id, tmp_table1.value FROM 
        tmp_table1 WHERE tmp_table1.value IS NOT NULL AND tmp_table1.value != '';
    DECLARE CONTINUE HANDLER FOR NOT FOUND SET done = 1;

    SET @expr = CONCAT('CREATE TEMPORARY TABLE tmp_table1 (id INT NOT NULL, value VARCHAR(255)) ENGINE=Memory SELECT ',
        id_column,' id, ', value_column,' value FROM ',tablename);
    PREPARE stmt FROM @expr;
    EXECUTE stmt;
    DEALLOCATE PREPARE stmt;

    DROP TEMPORARY TABLE IF EXISTS tmp_table2;
    CREATE TEMPORARY TABLE tmp_table2 (id INT NOT NULL, value VARCHAR(255) NOT NULL) ENGINE=Memory;

    OPEN cur;
      read_loop: LOOP
        FETCH cur INTO id, value;
        IF done THEN
          LEAVE read_loop;
        END IF;

        SET occurrences = (SELECT CHAR_LENGTH(value) -
                           CHAR_LENGTH(REPLACE(value, delim, '')) + 1);
        SET i=1;
        WHILE i <= occurrences DO
          SET splitted_value = (SELECT TRIM(SUBSTRING_INDEX(
              SUBSTRING_INDEX(value, delim, i), delim, -1)));
          INSERT INTO tmp_table2 VALUES (id, splitted_value);
          SET i = i + 1;
        END WHILE;
      END LOOP;

      SELECT * FROM tmp_table2;
    CLOSE cur;
    DROP TEMPORARY TABLE tmp_table1;
  END; $$

delimiter ;

사용 예 (정규화) :

CALL split_value_into_multiple_rows('my_contacts', 'contact_id', 'interests', ',');

CREATE TABLE interests (
  interest_id INT NOT NULL AUTO_INCREMENT PRIMARY KEY,
  interest VARCHAR(30) NOT NULL
) SELECT DISTINCT value interest FROM tmp_table2;

CREATE TABLE contact_interest (
  contact_id INT NOT NULL,
  interest_id INT NOT NULL,
  CONSTRAINT fk_contact_interest_my_contacts_contact_id FOREIGN KEY (contact_id) REFERENCES my_contacts (contact_id),
  CONSTRAINT fk_contact_interest_interests_interest_id FOREIGN KEY (interest_id) REFERENCES interests (interest_id)
) SELECT my_contacts.contact_id, interests.interest_id
    FROM my_contacts, tmp_table2, interests
    WHERE my_contacts.contact_id = tmp_table2.id AND interests.interest = tmp_table2.value;

---

CREATE PROCEDURE `getVal`()
BEGIN
        declare r_len integer;
        declare r_id integer;
        declare r_val varchar(20);
        declare i integer;
        DECLARE found_row int(10);
        DECLARE row CURSOR FOR select length(replace(val,"|","")),id,val from split;
        create table x(id int,name varchar(20));
      open row;
            select FOUND_ROWS() into found_row ;
            read_loop: LOOP
                IF found_row = 0 THEN
                         LEAVE read_loop;
                END IF;
            set i = 1;  
            FETCH row INTO r_len,r_id,r_val;
            label1: LOOP        
                IF i <= r_len THEN
                  insert into x values( r_id,SUBSTRING(replace(r_val,"|",""),i,1));
                  SET i = i + 1;
                  ITERATE label1;
                END IF;
                LEAVE label1;
            END LOOP label1;
            set found_row = found_row - 1;
            END LOOP;
        close row;
        select * from x;
        drop table x;
END

---

The original question was for MySQL and SQL in general. The example below is for the new versions of MySQL. Unfortunately, a generic query that would work on any SQL server is not possible. Some servers do no support CTE, others do not have substring_index, yet others have built-in functions for splitting a string into multiple rows.

--- the answer follows ---

Recursive queries are convenient when the server does not provide built-in functionality. They can also be the bottleneck.

The following query was written and tested on MySQL version 8.0.16. It will not work on version 5.7-. The old versions do not support Common Table Expression (CTE) and thus recursive queries.

with recursive
  input as (
        select 1 as id, 'a,b,c' as names
      union
        select 2, 'b'
    ),
  recurs as (
        select id, 1 as pos, names as remain, substring_index( names, ',', 1 ) as name
          from input
      union all
        select id, pos + 1, substring( remain, char_length( name ) + 2 ),
            substring_index( substring( remain, char_length( name ) + 2 ), ',', 1 )
          from recurs
          where char_length( remain ) > char_length( name )
    )
select id, name
  from recurs
  order by id, pos;

---

Here is my attempt: The first select presents the csv field to the split. Using recursive CTE, we can create a list of numbers that are limited to the number of terms in the csv field. The number of terms is just the difference in the length of the csv field and itself with all the delimiters removed. Then joining with this numbers, substring_index extracts that term.

with recursive
    T as ( select 'a,b,c,d,e,f' as items),
    N as ( select 1 as n union select n + 1 from N, T
        where n <= length(items) - length(replace(items, ',', '')))
    select distinct substring_index(substring_index(items, ',', n), ',', -1)
group_name from N, T

---

Here is my solution

-- Create the maximum number of words we want to pick (indexes in n)
with recursive n(i) as (
    select
        1 i
    union all
    select i+1 from n where i < 1000
)
select distinct
    s.id,
    s.oaddress,
    -- n.i,
    -- use the index to pick the nth word, the last words will always repeat. Remove the duplicates with distinct
    if(instr(reverse(trim(substring_index(s.oaddress,' ',n.i))),' ') > 0,
        reverse(substr(reverse(trim(substring_index(s.oaddress,' ',n.i))),1,
            instr(reverse(trim(substring_index(s.oaddress,' ',n.i))),' '))),
        trim(substring_index(s.oaddress,' ',n.i))) oth
from 
    app_schools s,
    n

참고URL : https://stackoverflow.com/questions/17942508/sql-split-values-to-multiple-rows