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一个词库数据库，其中术语和类别相互链接并运行 SQL Server 2008。基于此和此答案。这是一个示例：

CREATE TABLE #term (termid VARCHAR(8), en VARCHAR(32), enscope VARCHAR(32))
CREATE TABLE #link (linkid VARCHAR(10), termid VARCHAR(8), reltype VARCHAR(2), refid VARCHAR(8))
CREATE TABLE #categorylink (code VARCHAR(3), termid VARCHAR(8))

INSERT INTO #term VALUES ('100', 'ABC', 'abc_scopenote')
INSERT INTO #term VALUES ('120', 'DEF', 'def_scopenote')
INSERT INTO #term VALUES ('150', 'GHI', NULL)

INSERT INTO #link VALUES ('1', '100', 'NT', '120')
INSERT INTO #link VALUES ('2', '100', 'NT', '150')
INSERT INTO #link VALUES ('3', '120', 'BT', '100')
INSERT INTO #link VALUES ('4', '120', 'RT', '150')
INSERT INTO #link VALUES ('5', '150', 'BT', '100')
INSERT INTO #link VALUES ('6', '150', 'RT', '120')

INSERT INTO #categorylink VALUES ('S01', '100')
INSERT INTO #categorylink VALUES ('S02', '100')
INSERT INTO #categorylink VALUES ('B04', '150')

SELECT
       CASE
       WHEN #term.enscope IS NULL AND refterm.en IS NULL AND #categorylink.code IS NULL
       THEN #term.en
       ELSE NULL
       END,
       CHAR(9) + 'SN ' + #term.enscope,
       CHAR(9) + #link.reltype + CHAR(32) + refterm.en,
       CHAR(9) + 'CODE ' + #categorylink.code
    FROM #link
        INNER JOIN #term ON #term.termid = #link.termid
        INNER JOIN #term AS refterm ON refterm.termid = #link.refid
        LEFT JOIN #categorylink ON #term.termid = #categorylink.termid

    GROUP BY GROUPING SETS (#term.en, (#term.en, #term.enscope), (#term.en, #link.linkid, #link.reltype, refterm.en), (#term.en, #categorylink.code))
    ORDER BY #term.en, #categorylink.code, #link.linkid, #term.enscope
GO

DROP TABLE #term
DROP TABLE #link
DROP TABLE #categorylink
GO

如果'enscope'中有NULL，我有一个重复的行。

如果没有“categorylink”值，我有一个重复的行。

请问如何避免这种情况？

我想将它们全部合并到一个没有重复的列中。

; WITH CTEterm AS (
    SELECT
       ROW_NUMBER() OVER (PARTITION BY #term.en, refterm.en ORDER BY #term.en) AS rownumber,
       #term.en AS mainterm,
       CHAR(9) + 'SN ' + #term.enscope AS scopenote,
       CHAR(9) + #link.reltype + CHAR(32) + refterm.en AS subterms,
       CHAR(9) + 'CODE ' + #categorylink.code AS codes
    FROM #link
       INNER JOIN #term ON #term.termid = #link.termid
       INNER JOIN #term AS refterm ON refterm.termid = #link.refid
       LEFT JOIN #categorylink ON #term.termid = #categorylink.termid
)

SELECT COALESCE(
    CASE
    WHEN rownumber = 1
    THEN mainterm
    ELSE NULL
    END,
    scopenote,
    subterms,
    codes
)
FROM CTEterm
GROUP BY GROUPING SETS ((mainterm, rownumber), (mainterm, scopenote), (mainterm, subterms), (mainterm, codes))
ORDER BY mainterm, codes, subterms, scopenote

GO

基本上如何避免在 CASE 中使用 'ELSE NULL'（如 'else skip row'）？

这就是我使用 COALESCE 得到的

ABC
NULL
    SN abc_scopenote
    NT DEF
    NT GHI
    CODE S01
    CODE S02
NULL
DEF
    SN def_scopenote
    BT ABC
    RT GHI
NULL
GHI
    BT ABC
    RT DEF
    CODE B04

这就是我需要的

ABC
    SN abc_scopenote
    NT DEF
    NT GHI
    CODE S01
    CODE S02
DEF
    SN def_scopenote
    BT ABC
    RT GHI
GHI
    BT ABC
    RT DEF
    CODE B04

同样的问题在这里

4

1 回答 1

2

对不起，如果这不是你所期望的，但如果你只是需要摆脱 NULL，那么我不明白为什么你不能这样做：

;WITH CTEterm AS (
    SELECT
       ROW_NUMBER() OVER (PARTITION BY #term.en, refterm.en
                              ORDER BY #term.en) AS rownumber,
       #term.en AS mainterm,
       CHAR(9) + 'SN ' + #term.enscope AS scopenote,
       CHAR(9) + #link.reltype + CHAR(32) + refterm.en AS subterms,
       CHAR(9) + 'CODE ' + #categorylink.code AS codes
    FROM #link
       INNER JOIN #term ON #term.termid = #link.termid
       INNER JOIN #term AS refterm ON refterm.termid = #link.refid
       LEFT JOIN #categorylink ON #term.termid = #categorylink.termid
)
SELECT
  AggValue
FROM (
  SELECT
    mainterm, codes, subterms, scopenote,
    COALESCE(
      CASE WHEN rownumber = 1 THEN mainterm ELSE NULL END,
      scopenote,
      subterms,
      codes
    ) AS AggValue
  FROM CTEterm
  GROUP BY GROUPING SETS ((mainterm, rownumber), (mainterm, scopenote),
                          (mainterm, subterms), (mainterm, codes))
) s
WHERE AggValue IS NOT NULL
ORDER BY mainterm, codes, subterms, scopenote

注意：ELSE NULL在这里被删除只是因为它没有任何改变（NULL当没有时暗示ELSE），而不是因为你会从删除它中获得任何东西。

于 2011-06-18T01:12:07.083 回答