recursive-query

问题 I have a MySQL table which is as follows: id name parent_id 19 category1 0 20 category2 19 21 category3 20 22 category4 21 ... ... ... Now, I want to have a single MySQL query to which I simply supply the id [for instance say id=19 ] then I should get all its child ids [i.e. result should have ids '20,21,22'].... The hierarchy of the children is not known; it can vary.... I know how to do it using a for loop... but how to achieve the same using a single MySQL query? 回答1: For MySQL 8+: use the

问题 What I'm trying to do is take a record that looks like this: Start_DT End_DT ID 4/5/2013 4/9/2013 1 and change it to look like this: DT ID 4/5/2013 1 4/6/2013 1 4/7/2013 1 4/8/2013 1 4/9/2013 1 it can be done in Python but I am not sure if it is possible with SQL Oracle? I am having difficult time making this work. Any help would be appreciated. Thanks 回答1: connect by level is useful for these problems. suppose the first CTE named " table_DT " is your table name so you can use the select

问题 I'm having some trouble working out the PostgreSQL documentation for recursive queries, and wonder if anyone might be able to offer a suggestion for the following. Here's the data: Table "public.subjects" Column | Type | Collation | Nullable | Default -------------------+-----------------------------+-----------+----------+-------------------------------------- id | bigint | | not null | nextval('subjects_id_seq'::regclass) name | character varying | | | Table "public.subject_associations"

问题 I'm having some trouble working out the PostgreSQL documentation for recursive queries, and wonder if anyone might be able to offer a suggestion for the following. Here's the data: Table "public.subjects" Column | Type | Collation | Nullable | Default -------------------+-----------------------------+-----------+----------+-------------------------------------- id | bigint | | not null | nextval('subjects_id_seq'::regclass) name | character varying | | | Table "public.subject_associations"

问题 I do not know how to select query recursive.. id idparent jobNO -------------------------------- 1 0 1 2 1 2 3 1 3 4 0 4 5 4 5 6 4 6 how do the results like this With SqlServer id idparent jobNO ListJob ---------------------------------------- 1 0 1 1 2 1 2 1/2 3 1 3 1/3 4 0 4 4 5 4 5 4/5 6 5 6 4/5/6 回答1: You need to use a Recursive Common Table Expression. There are many useful articles online. Useful Links Simple Talk: SQL Server CTE Basics blog.sqlauthority: Recursive CTE Here is a

问题 I looked at Tim Hall's excellent article here, that allows you to work with self-referenced entities and show hierarchical data (starting with top level nodes and joining back recursively), using CTE like syntax in Oracle. So I have code that looks like this: WITH J1(JOBMST_ID, JOBMST_NAME, JOBMST_PRNTID, JOBMST_TYPE, LVL) AS ( SELECT JOBMST_ID, JOBMST_NAME, JOBMST_PRNTID, JOBMST_TYPE, 1 FROM TIDAL.JOBMST WHERE JOBMST_PRNTID IS NULL UNION ALL SELECT J2.JOBMST_ID,J2.JOBMST_NAME,J2.JOBMST

问题 I looked at Tim Hall's excellent article here, that allows you to work with self-referenced entities and show hierarchical data (starting with top level nodes and joining back recursively), using CTE like syntax in Oracle. So I have code that looks like this: WITH J1(JOBMST_ID, JOBMST_NAME, JOBMST_PRNTID, JOBMST_TYPE, LVL) AS ( SELECT JOBMST_ID, JOBMST_NAME, JOBMST_PRNTID, JOBMST_TYPE, 1 FROM TIDAL.JOBMST WHERE JOBMST_PRNTID IS NULL UNION ALL SELECT J2.JOBMST_ID,J2.JOBMST_NAME,J2.JOBMST

问题 SQL Server CREATE TABLE [TABLE_1] ( PLAN_NR decimal(28,6) NULL, START_DATE datetime NULL, MAX_PERIODS decimal(28,6) NULL, ); INSERT INTO TABLE_1 (PLAN_NR, START_DATE, MAX_PERIODS) VALUES (1, '2020-05-01', 8), (2, '2020-08-01', 8); SQL - FIDDLE I've got a table with the columns PLAN_NR , START_DATE and MAX_PERIODS . Each period is exactly 7 days long, unless the period contains a month end. Then the period should be divided into a range before the end of the month up to and including the last

问题 Here is the DB Structure I'm using Item ---- ID [PK] Name Desc Links ----- ID [FK] LID [FK] -- Link ID LType -- Link Type (Parent, Alias) Permission ---------- ID [FK] CanRead CanWrite CanDelete Let's assume, we have the below data in the table Item Table ----------- ID Name Desc ================= 0 Root Base Item 1 One First 2 Two Second 3 Three Third 4 Four Forth 5 Five Fifth 6 Six Sixth Links Table ----------- ID LID LType ================== 1 0 Parent 2 0 Parent 3 1 Parent 4 2 Parent 5 4

问题 Here is the DB Structure I'm using Item ---- ID [PK] Name Desc Links ----- ID [FK] LID [FK] -- Link ID LType -- Link Type (Parent, Alias) Permission ---------- ID [FK] CanRead CanWrite CanDelete Let's assume, we have the below data in the table Item Table ----------- ID Name Desc ================= 0 Root Base Item 1 One First 2 Two Second 3 Three Third 4 Four Forth 5 Five Fifth 6 Six Sixth Links Table ----------- ID LID LType ================== 1 0 Parent 2 0 Parent 3 1 Parent 4 2 Parent 5 4