最近使用Datax同步进行定时数据同步，并在同步完之后进行回调sql进行统计操作。对应的ORACLE表结构如下：

create table DATA_STAT_DAY (
DATA_DATE DATE, 
ID VARCHAR2(2), 
NAME VARCHAR2(2),
CLASSNO VARCHAR2(2),
SCORES NUMBER(16,0)
);

CREATE UNIQUE INDEX IDX_DATA_STAT_DAY ON DATA_STAT_DAY(DATA_DATE, ID, NAME, CLASSNO);

回调对应的SQL如下：

MERGE INTO DATA_STAT_DAY a
USING (
	SELECT 
	DATA_DATE,'0000' AS ID,NAME,CLASSNO, SUM(SCORES) SCORES
	FROM 
	DATA_STAT_DAY 
	WHERE ID % 2 = 0
	GROUP BY DATA_DATE,NAME,CLASSNO
) b 
ON (a.DATA_DATE = b.DATA_DATE and a.ID = b.ID and a.NAME = b.NAME and a.CLASSNO = b.CLASSNO)
WHEN MATCHED THEN 
	UPDATE SET a.SCORES = b.SCORES
WHEN NOT MATCHED THEN 
	INSERT INTO (a.DATA_DATE,a.ID,a.NAME,a.CLASSNO,a.SCORES)
	VALUES (b.DATA_DATE,b.ID,b.NAME,b.CLASSNO,b.SCORES)

回调SQL执行过程中，触发了 ORA-00001: unique constaint violated 的错误，其中USING部分的数据没有重复的，并且表中也没有和USING表中重复的，但是这里面的NAME和CLASSNO字段是有部分字段为NULL，ID部分有重复的值，然后这就导致了MERGE INTO的USING 关联的ON条件的时候判断为没关联上。但是在插入的时候，唯一索引判断重复了，所以对应的USING的数据集的ON部分的字段不能有为NULL的，否则会报唯一索引冲突的问题。

ORACLE的递归查询

SELECT M.MGT_ORG_CODE,
       LPAD(' ', LEVEL * 2, ' ') || M.MGT_ORG_NAME AS MGT_ORG_NAME,
       M.PRNT_MGT_ORG_CODE,
       SYS_CONNECT_BY_PATH(M.MGT_ORG_CODE, '>') AS CODE_PATH,
       REGEXP_SUBSTR(SYS_CONNECT_BY_PATH(M.MGT_ORG_CODE, '>'),'[^>]+',1,1,'i') AS MGT_ORG_C1,
       REGEXP_SUBSTR(SYS_CONNECT_BY_PATH(M.MGT_ORG_CODE, '>'),'[^>]+',1,2,'i') AS MGT_ORG_C2,
       REGEXP_SUBSTR(SYS_CONNECT_BY_PATH(M.MGT_ORG_CODE, '>'),'[^>]+',1,3,'i') AS MGT_ORG_C3,
       REGEXP_SUBSTR(SYS_CONNECT_BY_PATH(M.MGT_ORG_CODE, '>'),'[^>]+',1,4,'i') AS MGT_ORG_C4,
       REGEXP_SUBSTR(SYS_CONNECT_BY_PATH(M.MGT_ORG_CODE, '>'),'[^>]+',1,5,'i') AS MGT_ORG_C5,
       REGEXP_SUBSTR(SYS_CONNECT_BY_PATH(M.MGT_ORG_CODE, '>'),'[^>]+',1,6,'i') AS MGT_ORG_C6,
       CONNECT_BY_ROOT(M.MGT_ORG_CODE) AS ROOT_CODE_VAL,
       CONNECT_BY_ISLEAF AS ISLEAF,
       M.DIST_LV,
       '0' || (LEVEL + 1) AS MGT_LEVEL
  FROM (SELECT T.MGT_ORG_CODE,
               T.DIST_LV,
               T.PRNT_MGT_ORG_CODE,
               T.MGT_ORG_NAME
          FROM M_MGT_ORG T
         WHERE T.MGT_ORG_TYPE = 'corp'
           AND T.VALID_FLAG = '02') M
 START WITH M.DIST_LV = '02'
CONNECT BY NOCYCLE PRIOR M.MGT_ORG_CODE = M.PRNT_MGT_ORG_CODE
 ORDER BY M.MGT_ORG_CODE