I’d like to run a query like the one below against an Oracle 9i database from Java (an example table structure and example data are below).
SELECT deptno
, SUBSTR(comma_list, 2) comma_list
FROM (SELECT deptno
, SYS_CONNECT_BY_PATH(ename, ',') comma_list
, row_number
, row_count
FROM (SELECT deptno
, ename
, ROW_NUMBER()OVER(PARTITION BY deptno
ORDER BY empno) row_number
, COUNT(*)OVER(PARTITION BY deptno) row_count
FROM wd_emp)
START WITH row_number = 1
CONNECT BY deptno = PRIOR deptno
AND row_number = PRIOR row_number + 1)
WHERE row_number = row_count;
This works fine. However, if the sys_connect_by_path which builds up comma_list hits the varchar2 4000 character limit, then I get an “ORA-01489: result of string concatenation is too long” error.
Does anyone have any suggestions on how to overcome this limit so my concatenation can exceed 4000 characters?
Tables and example data:
CREATE TABLE WD_DEPT(DEPTNO NUMBER(2) CONSTRAINT PK_DEPT PRIMARY KEY
,DNAME VARCHAR2(14)
,LOC VARCHAR2(13));
CREATE TABLE WD_EMP(EMPNO NUMBER(4) CONSTRAINT PK_EMP PRIMARY KEY
,ENAME VARCHAR2(10)
,JOB VARCHAR2(10)
,MGR NUMBER(4)
,HIREDATE DATE
,SAL NUMBER(7,2)
,DEPTNO NUMBER(2) CONSTRAINT FK_DEPTNO REFERENCES WD_DEPT);
INSERT INTO WD_DEPT VALUES(10,'TEAM GREGORY','TABLE 3');
INSERT INTO WD_DEPT VALUES(20,'TEAM HANLEY','TABLE 2');
INSERT INTO WD_DEPT VALUES(30,'TEAM OFFIAH','TABLE 4');
INSERT INTO WD_DEPT VALUES(40,'TEAM BOTICA','TABLE 1');
INSERT INTO WD_DEPT VALUES(50,'TEAM SKERRETT','TABLE 4');
INSERT INTO WD_DEPT VALUES(60,'TEAM McGINTY','TABLE 1');
INSERT INTO WD_DEPT VALUES(70,'EMPTY TEAM','NO TABLE');
INSERT INTO WD_EMP VALUES(11,'GREGORY', 'TEAM LEAD', 28, to_date('18-JAN-2000', 'DD-MON-RRRR'), 800, 10);
INSERT INTO WD_EMP VALUES(12,'BELL', 'DEVELOPER', 11, to_date('17-JAN-2000', 'DD-MON-RRRR'), 600, 10);
INSERT INTO WD_EMP VALUES(13,'CLARKE', 'DEVELOPER', 11, to_date('16-JAN-2000', 'DD-MON-RRRR'), 600, 10);
INSERT INTO WD_EMP VALUES(14,'HANLEY', 'TEAM LEAD', 28, to_date('15-JAN-2000', 'DD-MON-RRRR'), 800, 20);
INSERT INTO WD_EMP VALUES(15,'BETTS', 'CONTRACTOR', 14, to_date('14-JAN-2000', 'DD-MON-RRRR'), 700, 20);
INSERT INTO WD_EMP VALUES(16,'MILES', 'CONTRACTOR', 14, to_date('13-JAN-2000', 'DD-MON-RRRR'), 700, 20);
INSERT INTO WD_EMP VALUES(17,'HAMPSON', 'DEVELOPER', 14, to_date('12-JAN-2000', 'DD-MON-RRRR'), 600, 20);
INSERT INTO WD_EMP VALUES(18,'PRESTON', 'DEVELOPER', 14, to_date('11-JAN-2000', 'DD-MON-RRRR'), 600, 20);
INSERT INTO WD_EMP VALUES(19,'OFFIAH', 'TEAM LEAD', 28, to_date('10-JAN-2000', 'DD-MON-RRRR'), 800, 30);
INSERT INTO WD_EMP VALUES(20,'PLATT', 'DEVELOPER', 19, to_date('09-JAN-2000', 'DD-MON-RRRR'), 600, 30);
INSERT INTO WD_EMP VALUES(21,'POTTER', 'DEVELOPER', 19, to_date('08-JAN-2000', 'DD-MON-RRRR'), 600, 30);
INSERT INTO WD_EMP VALUES(22,'CASE', 'DEVELOPER', 19, to_date('07-JAN-2000', 'DD-MON-RRRR'), 600, 30);
INSERT INTO WD_EMP VALUES(23,'BOTICA', 'TEAM LEAD', 28, to_date('06-JAN-2000', 'DD-MON-RRRR'), 800, 40);
INSERT INTO WD_EMP VALUES(24,'GILL', 'DEVELOPER', 23, to_date('05-JAN-2000', 'DD-MON-RRRR'), 600, 40);
INSERT INTO WD_EMP VALUES(25,'SKERRETT', 'TEAM LEAD', 28, to_date('04-JAN-2000', 'DD-MON-RRRR'), 800, 50);
INSERT INTO WD_EMP VALUES(26,'McGINTY', 'TEAM LEAD', 28, to_date('03-JAN-2000', 'DD-MON-RRRR'), 800, 60);
INSERT INTO WD_EMP VALUES(27,'LOWE', 'MANAGER', 28, to_date('02-JAN-2000', 'DD-MON-RRRR'), 900, NULL);
INSERT INTO WD_EMP VALUES(28,'MONIE', 'MANAGER', NULL, to_date('01-JAN-2000', 'DD-MON-RRRR'), 1000, NULL);
Is it necessary to build the comma-list in SQL?
Since you are running this from Java anyway, maybe you could query rows with “parent_id” ,”child_id”, “tree_level” columns and build the employee path in your application code ? I suppose you are splitting it into a List now anyway (a 4000 character string cannot be for direct display purposes).