SQL Server CTE 查询 - 行到单分隔字符串字段

Question

我在 SQL Server 中有以下数据:

数据创建:

-- First we create some test data.
CREATE TABLE E
(
     [Epinum] VARCHAR(9), 
     [RTyp] VARCHAR(120), 
     [Date] DATETIME
);
GO

INSERT INTO E ([Epinum], [RTyp], [Date])
VALUES ('1', '', CONVERT(datetime, '2002-11-26 14:18:00', 20)),
       ('2', '', CONVERT(datetime, '2002-11-24 15:15:00', 20)),
       ('3', '', CONVERT(datetime, '2002-12-17 11:12:00', 20)),
       ('4', '', CONVERT(datetime, '2002-12-09 19:57:00', 20)),
       ('5', '', CONVERT(datetime, '2002-12-11 06:00:00', 20)),
       ('6', '', CONVERT(datetime, '2002-12-19 12:31:00', 20)),
       ('7', '', CONVERT(datetime, '2002-12-15 08:39:00', 20)),
       ('8', '', CONVERT(datetime, '2002-12-20 08:39:00', 20)),
       ('9', '', CONVERT(datetime, '2002-12-13 08:39:00', 20)),
       ('10', '', CONVERT(datetime, '2002-12-16 08:39:00', 20)),
       ('11', '', CONVERT(datetime, '2002-12-14 08:39:00', 20));
GO

CREATE TABLE UJ
(
    [Epinum] VARCHAR(9), 
    [RTyp] VARCHAR(3)
);
GO

INSERT INTO UJ ([Epinum], [RTyp])
VALUES ('1', '111'), ('1', '222'), ('1', '333'), ('1', '444'),
       ('2', '111'),
       ('3', '111'), ('3', '222'), ('3', '333'),
       ('4', '111'),
       ('5', '111'), ('5', '222'), ('5', '333'), ('5', '444'), 
       ('5', '555'), ('5', '666'), ('5', '777'), ('5', '888'),
       ('7', '111'),
       ('8', '111'),
       ('9', '111'), ('9', '222');
GO

T-SQL 查询:

-- Now build a query that will create the data we want. 
;WITH Tmp AS
(
    SELECT 
        *, 
        ROW_NUMBER() OVER (PARTITION BY Epinum ORDER BY Epinum) AS rownum
    FROM 
        UJ 
) 
SELECT DISTINCT 
    Epinum, 
    (SELECT 
         RTyp + CASE 
                   WHEN t.rownum = (SELECT MAX(rownum) FROM Tmp WHERE Epinum = s.Epinum) 
                      THEN '' 
                      ELSE '|' 
                END 
     FROM Tmp AS t
     WHERE t.Epinum = s.Epinum 
     FOR XML PATH(''), TYPE).value('(.)[1]', 'VARCHAR(MAX)') AS Piped 
FROM 
    Tmp AS s;
GO

-- Great. Now we update the E table, joining on Epinum. 
;WITH Tmp AS
(
    SELECT 
        *, ROW_NUMBER() OVER (PARTITION BY Epinum ORDER BY Epinum) AS rownum
    FROM
        UJ 
) 
UPDATE E
SET e.RTyp = q.Piped 
FROM 
    (SELECT DISTINCT 
         Epinum, 
         (SELECT RTyp + CASE 
                           WHEN t.rownum = (SELECT MAX(rownum) FROM Tmp WHERE Epinum = s.Epinum) 
                              THEN '' 
                              ELSE '|' 
                        END 
          FROM Tmp AS t
          WHERE t.Epinum = s.Epinum 
          FOR XML PATH(''), TYPE).value('(.)[1]', 'VARCHAR(MAX)') AS Piped 
      FROM 
          Tmp AS s) AS q 
INNER JOIN 
    E AS e ON q.Epinum = e.Epinum;
GO

这会获取特定 Epinum 的所有 RTyp 列，然后对它们进行管道分隔并更新表 E 中的 RTyp。它效果很好，但问题是，生产中的表 E 约为 2.3M 行，UJ 约为 900k (两者都有更多的列)并且此查询执行更新所需的时间太长。

如何使该查询更加高效？

Answer 1

UPDATE E 
SET e.RTyp = q.Piped 
FROM (
    SELECT Epinum, Piped = STUFF(
        (SELECT '|' + RTyp 
         FROM UJ 
         WHERE Epinum = t.Epinum 
         FOR XML PATH ('')), 1, 1, '') 
    FROM UJ AS t 
    GROUP BY Epinum) AS q INNER JOIN E AS e 
        ON q.Epinum = e.Epinum;
GO