Copy hierarchical SQL Data in same Table with updated Values - php

Question

I have a table "projects" and a table "tasks" with hierarchical data in my SQL Database. So the tasks have subtasks which are linked with a "parent"-column to its parentID. The Root-Task-Parent is 0.
There is also a column "project_id" which refers the task to a specific project in the Project-Table. What i want to do now is to copy a whole task with all subtasks and refer it to a new project.
So the SQL-Query would be
INSERT INTO tasks (text, date, parent, projectid)
SELECT text, date, parent, 89
FROM tasks WHERE projectid = 23
where 23 is the id of the old project and 89 is the project to which the data is added.
But the problem is that it keeps the parent value, so my root task is copied properly, but the subtasks still refer to the old tasks. How can i update the parentID as well so the whole tasks and subtasks refer to the new Root Task?
I want to use this in my PHP-Web-Application for a Project-Management-Tool, so that the User can simply choose a "Master-Template" to copy its structure to a new project.
Thank you for your help!
Edit:
#Strawberry: I use dhtmlxgantt to create and update task but i want to solve it with SQL queries. An example Table would look like this:
Screenshot of Database
So in this case i would like to duplicate "Project" to "Project 2" with a new projectID and matching subtasks with parentIDs

Answer 1

I assume that [text] field is unique for each project.
With this assumption, here is my query
--DROP TABLE [Tasks]
-- Create table
CREATE TABLE [dbo].[Tasks](
[Id] [bigint] IDENTITY(1,1) NOT NULL,
[Text] [varchar](10) NOT NULL, -- Assume that [Text] field is unique for each project
[Name] [varchar](50) NOT NULL,
[ParentId] [bigint] NULL,
[ProjectId] [bigint] NOT NULL,
CONSTRAINT [PK_Tasks] PRIMARY KEY CLUSTERED
(
[Id] ASC
)
) ON [PRIMARY]
GO
SET ANSI_PADDING OFF
GO
ALTER TABLE [dbo].[Tasks] WITH CHECK ADD CONSTRAINT [FK_Tasks_Tasks] FOREIGN KEY([ParentId])
REFERENCES [dbo].[Tasks] ([Id])
GO
-- Remove all the data from the table and reseed the identity value
DELETE FROM [Tasks]
DBCC CHECKIDENT ('Tasks', RESEED, 1)
-- Sample Data population starts here...
INSERT INTO [Tasks] (text, Name, [ParentId], ProjectId)
SELECT 'A', 'A', null, 101 union ALL
SELECT 'B', 'B', null, 101 union ALL
SELECT 'C', 'C', null, 101
INSERT INTO [Tasks] (text, Name, [ParentId], ProjectId)
SELECT 'A1', 'A 1', (SELECT [Id] FROM [Tasks] WHERE [Text] = 'A'), 101 union ALL
SELECT 'A2', 'A 2', (SELECT [Id] FROM [Tasks] WHERE [Text] = 'A'), 101 union ALL
SELECT 'A3', 'A 3', (SELECT [Id] FROM [Tasks] WHERE [Text] = 'A'), 101 union ALL
SELECT 'A4', 'A 4', (SELECT [Id] FROM [Tasks] WHERE [Text] = 'A'), 101 union ALL
SELECT 'B1', 'B 1', (SELECT [Id] FROM [Tasks] WHERE [Text] = 'B'), 101 union ALL
SELECT 'B2', 'B 2', (SELECT [Id] FROM [Tasks] WHERE [Text] = 'B'), 101 union ALL
SELECT 'B3', 'B 3', (SELECT [Id] FROM [Tasks] WHERE [Text] = 'B'), 101 union ALL
SELECT 'C1', 'C 1', (SELECT [Id] FROM [Tasks] WHERE [Text] = 'C'), 101 union ALL
SELECT 'C2', 'C 2', (SELECT [Id] FROM [Tasks] WHERE [Text] = 'C'), 101 union ALL
SELECT 'C3', 'C 3', (SELECT [Id] FROM [Tasks] WHERE [Text] = 'C'), 101
INSERT INTO [Tasks] (text, Name, [ParentId], ProjectId)
SELECT 'A11', 'A 11', (SELECT [Id] FROM [Tasks] WHERE [Text] = 'A 1'), 101 union ALL
SELECT 'A41', 'A 41', (SELECT [Id] FROM [Tasks] WHERE [Text] = 'A 4'), 101
-- Sample Data population ends here...
GO
-- Copy all the data from project 101 and insert it as 102 with parent id as null
INSERT INTO [Tasks] (text, Name, [ParentId], ProjectId) -- other column names can be here...
SELECT text, Name, null, 102 -- Other column values can be here...
FROM [Tasks] where ProjectId = 101
-- Update the parent id using the text field
UPDATE A
SET A.[ParentId] = C.NewParentId
FROM [Tasks] A
INNER JOIN (SELECT Child.text, Parent.[Text] Parenttext
FROM [Tasks] Child
INNER JOIN [Tasks] Parent
ON Child.[ParentId] = Parent.[Id]
WHERE Child.ProjectId = 101
) B
ON A.[Text] = B.[Text]
LEFT JOIN (
SELECT [Id] NewParentId, [Text]
FROM [Tasks]
WHERE ProjectId = 102
) C
ON B.Parenttext = C.text
WHERE ProjectId = 102
SELECT * FROM [Tasks] WHERE ProjectId = 102 Order By [Text]
I hope this may help you