hierarchical-query

问题 Suppose that we have following tables create table Employee( 2 EMPNO NUMBER(3), 3 ENAME VARCHAR2(15 BYTE), 4 HIREDATE DATE, 5 ORIG_SALARY NUMBER(6), 6 CURR_SALARY NUMBER(6), 7 REGION VARCHAR2(1 BYTE), 8 MANAGER_ID NUMBER(3) 9 ) and create table job ( 2 EMPNO NUMBER(3), 3 jobtitle VARCHAR2(20 BYTE) 4 ) 5 / I am interested in what the below query does SELECT empno, manager_id, ename 2 FROM employee 3 START WITH empno = 1 4 CONNECT BY PRIOR empno = manager_id; As I understood this code selects

问题 Suppose that we have following tables create table Employee( 2 EMPNO NUMBER(3), 3 ENAME VARCHAR2(15 BYTE), 4 HIREDATE DATE, 5 ORIG_SALARY NUMBER(6), 6 CURR_SALARY NUMBER(6), 7 REGION VARCHAR2(1 BYTE), 8 MANAGER_ID NUMBER(3) 9 ) and create table job ( 2 EMPNO NUMBER(3), 3 jobtitle VARCHAR2(20 BYTE) 4 ) 5 / I am interested in what the below query does SELECT empno, manager_id, ename 2 FROM employee 3 START WITH empno = 1 4 CONNECT BY PRIOR empno = manager_id; As I understood this code selects

问题 Suppose that we have following tables create table Employee( 2 EMPNO NUMBER(3), 3 ENAME VARCHAR2(15 BYTE), 4 HIREDATE DATE, 5 ORIG_SALARY NUMBER(6), 6 CURR_SALARY NUMBER(6), 7 REGION VARCHAR2(1 BYTE), 8 MANAGER_ID NUMBER(3) 9 ) and create table job ( 2 EMPNO NUMBER(3), 3 jobtitle VARCHAR2(20 BYTE) 4 ) 5 / I am interested in what the below query does SELECT empno, manager_id, ename 2 FROM employee 3 START WITH empno = 1 4 CONNECT BY PRIOR empno = manager_id; As I understood this code selects

问题 Suppose that we have following tables create table Employee( 2 EMPNO NUMBER(3), 3 ENAME VARCHAR2(15 BYTE), 4 HIREDATE DATE, 5 ORIG_SALARY NUMBER(6), 6 CURR_SALARY NUMBER(6), 7 REGION VARCHAR2(1 BYTE), 8 MANAGER_ID NUMBER(3) 9 ) and create table job ( 2 EMPNO NUMBER(3), 3 jobtitle VARCHAR2(20 BYTE) 4 ) 5 / I am interested in what the below query does SELECT empno, manager_id, ename 2 FROM employee 3 START WITH empno = 1 4 CONNECT BY PRIOR empno = manager_id; As I understood this code selects

问题 I start to work with sql and I faced up with hierarchical queries. meanwhile I success to select the rows with connect by prior command but failed to update. Here is my update query: update HTABLE set status = 'INACTIVE' WHERE STATUS <> 'CLOSE' Connect by prior PARENT_ID=ID start with PARENT_ID=12345; I got SQL Error: ORA-00933: SQL command not properly ended and will be glad to know how to update table using hierarchically.. Thanks! EDIT I also tried to put the where condition in the start

问题 I have a hierarchical database strucutre, e.g. columns ID and PARENT_ID defined for each row, with the top level rows having a NULL PARENT_ID . I have all the relationships from this table flattened into another table, e.g. if there were three records in a single hierarchy of grandparent, parent, grandchild, there would be 3 records: **ANCESTOR, DESCENDANT** grantparent, parent grandparent, grandchild parent, grandchild Rather than execute a hierarchical query to determine that the grandchild

问题 Does PostgreSQL have a pseudo-column like "LEVEL" in Oracle? If not, then how can we create a column similar to "LEVEL"? 回答1: Postgres does not have hierarchical queries. No CONNECT BY , therefore also no LEVEL . The additional module tablefunc provides the function connectby() doing almost the same. See: What is the equivalent PostgreSQL syntax to Oracle's CONNECT BY ... START WITH? Or you can do similar things with a standard recursive CTE and a level column that's incremented with every

问题 Does PostgreSQL have a pseudo-column like "LEVEL" in Oracle? If not, then how can we create a column similar to "LEVEL"? 回答1: Postgres does not have hierarchical queries. No CONNECT BY , therefore also no LEVEL . The additional module tablefunc provides the function connectby() doing almost the same. See: What is the equivalent PostgreSQL syntax to Oracle's CONNECT BY ... START WITH? Or you can do similar things with a standard recursive CTE and a level column that's incremented with every

问题 Oracle SQL can do hierarchical queries since v2, using their proprietary CONNECT BY syntax. In their latest 11g release 2, they added recursive subquery factoring, also known as the recursive with clause. This is the ANSI standard, and if I understand correctly, this one has been implemented by other RDBMS vendors as well. When comparing the connect-by with the recursive with, I noticed a difference in the result set when using cycle detection. The connect by results are more intuitive to me,

问题 i have a table in which two fields are id, controlflag.It looks like Id CntrlFlag 121 SSSSSRNNNSSRSSNNR 122 SSSNNRRSSNNRSSSSS 123 RRSSSNNSSSSSSSSSSSSSSS I have to get output in the following form( the occurences of R) Id Flag 121 6,12,17 122 6,7,12 123 1,2 I tried oracle query( as i obtained from this forum): select mtr_id,listagg(str,',') within group (order by lvl) as flags from ( select mtr_id, instr(mtr_ctrl_flags,'R', 1, level) as str, level as lvl from mer_trans_reject connect by level