如何在PostgreSQL中更新引用表時違反重複鍵約束（Unique_Violation）？

Question

在PostgreSQL 9.1版中，我有兩個表：ICD9和Dx。我現在希望通過將現有記錄更改爲不同的鍵值（在cdesc中）來更新父表ICD9。

如果新的密鑰（cicd9，cdesc）不存在在ICD9表，然後將新值級聯到子表，DX :-)

但是，如果「新」與關鍵cdesc的新值已經存在於ICD9表中，則記錄未更新，因爲

錯誤23505：重複鍵值違反唯一約束「constraint_cdesc」。

我需要發生的是，父表，ICD9的更新，更新舊的記錄到新的價值觀和本次更新級聯到DX所有的孩子記錄所使用的舊密鑰，然後刪除ICD9表中現在未使用的「舊」記錄。

任何幫助這個新手將不勝感激。 TIA

CREATE TABLE icd9 
(
cicd9 character varying(8), 
cdesc character varying(80) NOT NULL, 
CONSTRAINT constraint_cdesc UNIQUE (cicd9, cdesc), 
CONSTRAINT desccheck CHECK (cdesc::text <> ''::text) 
) 

CREATE TABLE dx 
(
    cicd9 character varying(8), 
    cdesc character varying(80) NOT NULL, 
    CONSTRAINT fk_icd9 FOREIGN KEY (cicd9, cdesc) 
     REFERENCES icd9 (cicd9, cdesc) MATCH SIMPLE 
     ON UPDATE CASCADE ON DELETE RESTRICT DEFERRABLE INITIALLY DEFERRED 
) 

編輯＃1：我想我簡化了這些表結構，以澄清我的觀點，這裏是完整的結構。任何幫助，這是非常感謝。

CREATE TABLE dx 
(
recid serial NOT NULL, 
cpatient character varying(33) NOT NULL, 
cicd9 character varying(8), 
cdesc character varying(80) NOT NULL, 
tposted timestamp without time zone NOT NULL, 
"timestamp" timestamp without time zone DEFAULT now(), 
modified timestamp without time zone DEFAULT now(), 
resolved boolean DEFAULT false, 
treated boolean DEFAULT false, 
chronic boolean DEFAULT false, 
groupid character varying(33) NOT NULL, 
service integer DEFAULT 0, 
pmh boolean DEFAULT false, 
explanation text, 
CONSTRAINT pk_dx_recid PRIMARY KEY (recid), 
CONSTRAINT dx_cpatient_fkey FOREIGN KEY (cpatient) 
    REFERENCES patients (cpatient) MATCH SIMPLE 
    ON UPDATE CASCADE ON DELETE RESTRICT, 
CONSTRAINT dx_groupid_fkey FOREIGN KEY (groupid) 
    REFERENCES charts (groupid) MATCH SIMPLE 
    ON UPDATE CASCADE ON DELETE RESTRICT, 
CONSTRAINT fk_icd9 FOREIGN KEY (cicd9, cdesc) 
    REFERENCES icd9 (cicd9, cdesc) MATCH SIMPLE 
    ON UPDATE CASCADE ON DELETE RESTRICT DEFERRABLE INITIALLY DEFERRED, 
CONSTRAINT noduplicate_dx UNIQUE (cicd9, cdesc, groupid, tposted), 
CONSTRAINT desccheck CHECK (cdesc::text <> ''::text), 
CONSTRAINT groupcheck CHECK (groupid::bpchar <> ''::bpchar), 
CONSTRAINT patientcheck CHECK (cpatient::bpchar <> ''::bpchar) 
) 
WITH (
    OIDS=FALSE 
); 
ALTER TABLE dx 
OWNER TO postgres; 


    CREATE TABLE icd9 
    (
    recid serial NOT NULL, 
    cicd9 character varying(8), 
    cdesc character varying(80) NOT NULL, 
    "timestamp" timestamp without time zone DEFAULT now(), 
    modified timestamp without time zone DEFAULT now(), 
chronic boolean NOT NULL DEFAULT false, 
common boolean NOT NULL DEFAULT false, 
CONSTRAINT pk_icd9_recid PRIMARY KEY (recid), 
CONSTRAINT constraint_cdesc UNIQUE (cicd9, cdesc), 
CONSTRAINT desccheck CHECK (cdesc::text <> ''::text) 
) 
    WITH (
    OIDS=FALSE 
); 
ALTER TABLE icd9 
    OWNER TO postgres; 

Answer 1

從表的設計可能錯誤

之外，我找不到任何的臨時中止「unique_violation」它來自更新記錄的鍵值由另一個記錄的價值觀的方式。在上面的設計中，ICD9文件的目的是作爲一個庫，其中記錄可以或不可以在系統中的其他地方使用。

此問題的解決方案是從引用庫的表中移動子記錄，然後刪除會導致衝突的記錄。大部分代碼來自Finding Foreign Keys with No Indexes，並特別感謝@Patrick提供了我需要的最終密鑰來完成這項工作。下面是代碼（適用於我）執行這項工作。希望它有助於某人。

CREATE OR REPLACE FUNCTION g_saveicd9(ocicd9 text, ocdesc text, ncicd9 text, ncdesc text, nchronic boolean, ncommon boolean) 
    RETURNS void AS 
$BODY$ 
DECLARE 
    -- Declare row format 
    o ICD9%rowtype; 
    n ICD9%rowtype; 

BEGIN 
    -- Existing key values 
    o.cicd9 := ocicd9; 
    o.cdesc := ocdesc; 

    -- New record values 
    n.cicd9 := ncicd9; 
    n.cdesc := ncdesc; 
    n.chronic := nchronic; 
    n.common := ncommon; 

    -- Must set contraints all immediate to trigger constraints immediately for exceptions. 
    SET CONSTRAINTS ALL IMMEDIATE; 

    BEGIN 
     -- Edit ICD9 record. 
     UPDATE icd9 SET 
      cicd9 = n.cicd9, cdesc = n.cdesc, chronic = n.chronic, common = n.common 
     WHERE 
      cicd9 = o.cicd9 and cdesc = o.cdesc; 

     IF FOUND THEN 
     -- Successfully changed an existing record to new values. (The new value did not already exist). Exit function. 
      RETURN; 
     END IF; 

     EXCEPTION     

      WHEN unique_violation THEN 

       -- The new key already exists, so need to manually move all children to the "new" key. 
       PERFORM merge_children_of_icd9(o.cicd9, o.cdesc, n.cicd9, n.cdesc); 

       -- Remove the old key values from ICD9 
       DELETE FROM icd9 
        WHERE cicd9 = o.cicd9 and cdesc = o.cdesc; 

       -- Update existing record. 
       UPDATE icd9 SET 
         chronic = n.chronic, common = n.common 
         WHERE 
         cicd9 = n.cicd9 and cdesc = n.cdesc; 

       RETURN; -- Exit function. 
    END;  

    -- No record found to update, so create new record.  
    BEGIN 
     INSERT INTO icd9(
      cicd9, cdesc, chronic, common) 
     VALUES ( 
      n.cicd9, n.cdesc, n.chronic, n.common); 

     -- Successfully inserted a new icd9 record, so exit function. This line is not reached if INSERT throws an exception. 
     RETURN; 

     EXCEPTION     

      WHEN unique_violation THEN 

       -- Key (o.cicd9,o.cdesc) not found for update, but target key (n.cicd9,n.cdesc) already exists. 
       -- Update target record with non-key values. 
       UPDATE icd9 SET 
         chronic = n.chronic, common = n.common 
        WHERE 
         cicd9 = n.cicd9 and cdesc = n.cdesc; 

       RETURN;     

    END; 

END; 
$BODY$ 
    LANGUAGE plpgsql VOLATILE 
    COST 100; 
ALTER FUNCTION g_saveicd9(text, text, text, text, boolean, boolean) 
    OWNER TO postgres; 


CREATE OR REPLACE FUNCTION merge_children_of_icd9(ocicd9 text, ocdesc text, ncicd9 text, ncdesc text) 
    RETURNS void AS 
$BODY$ 

DECLARE 
    r RECORD; 

BEGIN 
    FOR r IN 

     WITH fk_actions (code, action) AS (
      VALUES ('a', 'error'), 
       ('r', 'restrict'), 
       ('c', 'cascade'), 
       ('n', 'set null'), 
       ('d', 'set default') 
     ), 
     fk_list AS (
      SELECT pg_constraint.oid as fkoid, conrelid, confrelid::regclass as parentid, 
      conname, relname, nspname, 
      fk_actions_update.action as update_action, 
      fk_actions_delete.action as delete_action, 
      conkey as key_cols 
      FROM pg_constraint 
      JOIN pg_class ON conrelid = pg_class.oid 
      JOIN pg_namespace ON pg_class.relnamespace = pg_namespace.oid 
      JOIN fk_actions AS fk_actions_update ON confupdtype = fk_actions_update.code 
      JOIN fk_actions AS fk_actions_delete ON confdeltype = fk_actions_delete.code 
      WHERE contype = 'f' 
     ), 
     fk_attributes AS (
      SELECT fkoid, conrelid, attname, attnum 
      FROM fk_list 
      JOIN pg_attribute 
       ON conrelid = attrelid 
       AND attnum = ANY(key_cols) 
      ORDER BY fkoid, attnum 
     ), 
     fk_cols_list AS (
      SELECT fkoid, array_agg(attname) as cols_list 
      FROM fk_attributes 
      GROUP BY fkoid 
     ) 
     SELECT fk_list.fkoid, fk_list.conrelid, fk_list.parentid, fk_list.conname, fk_list.relname, fk_cols_list.cols_list 
     FROM fk_list 
     JOIN fk_cols_list USING (fkoid) 
     WHERE parentid = 'icd9'::regclass 

    LOOP 

     -- In an UPDATE statement in PL/pgSQL, the table name has to be given as a literal. If you want to dynamically set the 
     -- table name and the columns, use the EXECUTE command and paste the query string together. 
     -- The USING clause can only be used for substituting data values. 
     -- cols_list[1] is cicd9. cols_list[2] is cdesc. 

     EXECUTE 'UPDATE ' || quote_ident(r.relname) || 
      ' SET ' || quote_ident(r.cols_list[1]) || ' = $1, ' 
         || quote_ident(r.cols_list[2]) || ' = $2' || 
      ' WHERE ' || quote_ident(r.cols_list[1]) || ' = $3 AND ' 
         || quote_ident(r.cols_list[2]) || ' = $4' 
     USING ncicd9, ncdesc, ocicd9, ocdesc; 

    END LOOP;  

RETURN; 
END 
$BODY$ 
    LANGUAGE plpgsql VOLATILE 
    COST 100; 
ALTER FUNCTION merge_children_of_icd9(text, text, text, text) 
    OWNER TO postgres;