— 原始数据
— a 111
— b 222
— a 333
— a 444
— b 555
— 最终结果
— a 111*333*444

SELECT
L4.L_TIME
,MAX(SUBSTR(L4.分组内容,2)) 最终字段值
FROM(
        SELECT
        L3.L_TIME
        ,SYS_CONNECT_BY_PATH(L3.L_CONTENT,'*') AS 分组内容
        FROM(
                SELECT
                L2.L_TIME
                ,L2.L_CONTENT
                ,L2.L_TIME||L2.分组内编号 AS 分组字段加编号,L2.L_TIME||(L2.分组内编号-1) AS 上级分组字段加编号
                FROM(
                        SELECT
                        L1.L_TIME   -- 分组依据
                        ,L1.L_CONTENT    -- 同一列中 要合并的不同行 的值
                        ,ROW_NUMBER() OVER (PARTITION BY L1.L_TIME ORDER BY L1.L_CONTENT ASC) 分组内编号
                        FROM LOGS L1
                ) L2
        ) L3
        START WITH L3.上级分组字段加编号 LIKE '%0'
        CONNECT BY PRIOR L3.分组字段加编号=L3.上级分组字段加编号
) L4  

WHERE L_TIME='111'
GROUP BY L4.L_TIME  

-- ROW_NUMBER() OVER(PARTITION BY A ORDER BY B DESC) 新列名
-- 根据A分组，在分组内部根据B排序，而此函数计算的值就表示每组内部排序后的顺序编号（组内连续的唯一的)  

-- SYS_CONNECT_BY_PATH 函数： 第一个参数是形成树形式的字段，第二个参数是父级和其子级分隔显示用的分隔符
-- CONNECT BY PRIOR 是标示父子关系的对应
-- START WITH 代表你要开始遍历的的节点  

------------------------------------------------------------------------------------------
------------------------------------------------------------------------------------------
附上建表语句：  

DROP TABLE LOGS;
CREATE TABLE LOGS (
L_ID VARCHAR2(32) NOT NULL ,
L_CONTENT VARCHAR2(512)  ,
L_TIME VARCHAR2(32) ,
L_USER VARCHAR2(32) ,
PRIMARY KEY (L_ID)
);   

COMMENT ON TABLE LOGS IS '日志表';
COMMENT ON COLUMN LOGS.L_ID IS '日志ID';
COMMENT ON COLUMN LOGS.L_CONTENT IS '日志内容';
COMMENT ON COLUMN LOGS.L_TIME IS '时间';
COMMENT ON COLUMN LOGS.L_USER IS '操作人';  

INSERT INTO LOGS (L_ID, L_CONTENT, L_TIME, L_USER)  VALUES ('123', '黑啊', '111', '12345');
INSERT INTO LOGS (L_ID, L_CONTENT, L_TIME, L_USER)  VALUES ('124', '白啊', '222', '123456');
INSERT INTO LOGS (L_ID, L_CONTENT, L_TIME, L_USER)  VALUES ('125', '黑白啊', '111', '1234567');
INSERT INTO LOGS (L_ID, L_CONTENT, L_TIME, L_USER)  VALUES ('126', '白白啊', '111', '12345');
INSERT INTO LOGS (L_ID, L_CONTENT, L_TIME, L_USER)  VALUES ('127', '嘿嘿啊', '222', '123456');