Select / Delete of Three self referencing many to many relationships SQL Query - tsql

Question

I have a table ProjectLayerContent designed as following:
ProjectLayerContentID [INT]
ProjectLayerContentName [NVARCHAR(200)]
ProjectLayerContentParentID [INT]
ScopeIsProjectLayerContent [BIT]
ScopeIsProjectLayerContentID [INT]
DataTypeIsContentOfContent [BIT]
ContentOfContentID [INT]
The project layer content might have a parent, and might not, also the same for the children.
The project layer content scope might include another project layer content.
The project layer content data type might be a type of another content.
What I am trying to do is in the delete process, I want to show a list includes the count of what's is going to be deleted if you will delete this project layer content.
Pretty much this is what I got into, but I know those results isn't right
DECLARE #ProjectLayerContentID INT = 1;
DECLARE #resTable TABLE (
ProjectLayerContentIDP int,
ProjLContentType nvarchar(100));
DECLARE #ProjectLayerContentIDRecursionParam int;
DECLARE #Type NVARCHAR(MAX);
DECLARE #resultString NVARCHAR(MAX) = '';
-- SELECT Project layer content children with recursion
-- SELECT the count of the result from the recursion of the children of the project layer content id passed with the sql parameter in the query
DECLARE ProjectLayerContentChildren_Cursor CURSOR FOR
SELECT ProjectLayerContentID, 'Child(ren)'
FROM ProjectLayerContent
WHERE ProjectLayerContentParentID = #ProjectLayerContentID
OPEN ProjectLayerContentChildren_Cursor
FETCH NEXT FROM ProjectLayerContentChildren_Cursor INTO #ProjectLayerContentIDRecursionParam, #Type
WHILE ##FETCH_STATUS = 0
BEGIN
INSERT INTO #resTable SELECT #ProjectLayerContentIDRecursionParam, #Type;
;WITH ProjectLayerContentTotalScopeChildren AS(
SELECT ProjectLayerContentID,CAST('Content(s) of Child(ren)' as varchar(259)) AS ProjLContentType
FROM ProjectLayerContent
WHERE ContentOfContentID = #ProjectLayerContentIDRecursionParam
UNION ALL
SELECT Scopechildren.ProjectLayerContentID, CAST('Children Content Of Content of Child(ren)' as varchar(259)) AS ProjLContentType
FROM ProjectLayerContent Scopechildren INNER JOIN
ProjectLayerContentTotalScopeChildren projLContents ON Scopechildren.ContentOfContentID = projLContents.ProjectLayerContentID
UNION ALL
SELECT children.ProjectLayerContentID, CAST('Child(ren) of Child(ren) of Child(ren)' as varchar(259)) AS ProjLContentType
FROM ProjectLayerContent children INNER JOIN
ProjectLayerContentTotalScopeChildren projLContents ON children.ProjectLayerContentParentID = projLContents.ProjectLayerContentID
)
INSERT INTO #resTable SELECT ProjectLayerContentID, ProjLContentType from ProjectLayerContentTotalScopeChildren
FETCH NEXT FROM ProjectLayerContentChildren_Cursor INTO #ProjectLayerContentIDRecursionParam, #Type
END
-- close the cursor
CLOSE ProjectLayerContentChildren_Cursor
DEALLOCATE ProjectLayerContentChildren_Cursor
-----------------------------------------------------------------------------------------------------------
-- SELECT Project layer content Scope children with recursion
DECLARE ProjectLayerContent_Cursor CURSOR FOR
SELECT ProjectLayerContentID, 'Content Of Content'
FROM ProjectLayerContent
WHERE ContentOfContentID = #ProjectLayerContentID
OPEN ProjectLayerContent_Cursor
FETCH NEXT FROM ProjectLayerContent_Cursor INTO #ProjectLayerContentIDRecursionParam, #Type
WHILE ##FETCH_STATUS = 0
BEGIN
INSERT INTO #resTable SELECT #ProjectLayerContentIDRecursionParam, #Type;
;WITH ProjectLayerContentTotalScopeContentOfContent AS(
SELECT ProjectLayerContentID,CAST('Children Content Of Content' as varchar(259)) AS ProjLContentType
FROM ProjectLayerContent
WHERE ContentOfContentID = #ProjectLayerContentIDRecursionParam
UNION ALL
SELECT Scopechildren.ProjectLayerContentID, CAST('Children Content Of Content of Children Content Of Content' as varchar(259)) AS ProjLContentType
FROM ProjectLayerContent Scopechildren INNER JOIN
ProjectLayerContentTotalScopeContentOfContent projLContents ON Scopechildren.ContentOfContentID = projLContents.ProjectLayerContentID
UNION ALL
SELECT children.ProjectLayerContentID, CAST('Children of Children Content Of Content' as varchar(259)) AS ProjLContentType
FROM ProjectLayerContent children INNER JOIN
ProjectLayerContentTotalScopeContentOfContent projLContents ON children.ProjectLayerContentParentID = projLContents.ProjectLayerContentID
)
INSERT INTO #resTable SELECT ProjectLayerContentID, ProjLContentType from ProjectLayerContentTotalScopeContentOfContent
FETCH NEXT FROM ProjectLayerContent_Cursor INTO #ProjectLayerContentIDRecursionParam, #Type
END
-- close the cursor
CLOSE ProjectLayerContent_Cursor
DEALLOCATE ProjectLayerContent_Cursor
--select the result to present it.
SELECT * FROM #resTable;
Thanks in advance.

Answer 1

I found that this solution to get the needed functionality as needed.
I created the stored procedure to get all children for this project layer first, and created a table to add the result in. Because one of the first error to apply this solution was INSERT INTO EXEC wouldn't work if you have a chain of stored procedures calling each other. It only works for the first time, but the other times will show an error.
DECLARE #ProjectLayerContentID INT = 1;
DECLARE #ProjectLayerContentIDRecursionParam INT;
DECLARE #Type NVARCHAR(MAX);
DECLARE #resultString NVARCHAR(MAX) = '';
-------Create temp table to insert the results into it
CREATE TABLE #ResTable(
ProjectLayerContentIDP int,
ProjLContentType nvarchar(100));
Then I created a cursor for the select statement of all children who have that relationship of being child of this project layer, or being content of it.
-- SELECT Project layer content children with recursion
-- SELECT the count of the result from the recursion of the children of the project layer content id passed with the sql parameter in the query
DECLARE ProjectLayerContent_Cursor CURSOR FOR
SELECT ProjectLayerContentID, CASE WHEN ProjectLayerContentParentID = #ProjectLayerContentID THEN 'Child(ren)' ELSE 'Content(s) of Content(s)' END
FROM ProjectLayerContent
WHERE ProjectLayerContentParentID = #ProjectLayerContentID
OR ContentOfContentID = #ProjectLayerContentID
OPEN ProjectLayerContent_Cursor
FETCH NEXT FROM ProjectLayerContent_Cursor INTO #ProjectLayerContentIDRecursionParam, #Type
WHILE ##FETCH_STATUS = 0
BEGIN
INSERT INTO #ResTable SELECT #ProjectLayerContentIDRecursionParam, #Type;
Then I will call the recursion stored procedure to get each of the current project layer content chlidren, and content of the children.
Exec DeleteCheck_ProjectLayerContentChildren #ProjectLayerContentIDRecursionParam;
FETCH NEXT FROM ProjectLayerContent_Cursor INTO #ProjectLayerContentIDRecursionParam, #Type
END
-- close the cursor
CLOSE ProjectLayerContent_Cursor
DEALLOCATE ProjectLayerContent_Cursor
At this part here, we will select the results, and then drop the temp table from the database server.
--select the result to present it.
SELECT #resultString = #resultString + '<br/><u>' + CONVERT(NVARCHAR(MAX), Count(ProjectLayerContentIDP)) + '</u> ' + ProjLContentType
FROM #ResTable
GROUP BY ProjLContentType;
SELECT #resultString;
DROP TABLE #ResTable
Here is the recursion stored procedure that we called already in the previous query
CREATE PROCEDURE [dbo].[DeleteCheck_ProjectLayerContentChildren]
#ProjectLayerContentID INT
AS
BEGIN
DECLARE #ProjectLayerContentIDRecursionParam INT;
DECLARE #Type NVARCHAR(MAX);
-- SELECT Project layer content children with recursion
-- SELECT the count of the result from the recursion of the children of the project layer content id passed with the sql parameter in the query.
Notice here we added Local into the deceleration of the cursor, because it will show an error of creating the cursor with the same name
DECLARE ProjectLayerContentChildren_Cursor CURSOR LOCAL FOR
SELECT ProjectLayerContentID, CASE WHEN ProjectLayerContentParentID = #ProjectLayerContentID THEN 'Child(ren) of Child(ren)' ELSE 'Child(ren) Content(s) of Content(s)' END
FROM ProjectLayerContent
WHERE ProjectLayerContentParentID = #ProjectLayerContentID
OR ContentOfContentID = #ProjectLayerContentID
Pretty much most of this query is the same, as the previous one, but this is for the project layer content children of children counts, and we don't create the result table again because it will be already created, then we just add the result, and we have the needed functionality, and you can apply it to more than two or three self relationships.
OPEN ProjectLayerContentChildren_Cursor
FETCH NEXT FROM ProjectLayerContentChildren_Cursor INTO #ProjectLayerContentIDRecursionParam, #Type
WHILE ##FETCH_STATUS = 0
BEGIN
INSERT INTO #ResTable SELECT #ProjectLayerContentIDRecursionParam, #Type;
Exec DeleteCheck_ProjectLayerContentChildren #ProjectLayerContentIDRecursionParam
FETCH NEXT FROM ProjectLayerContentChildren_Cursor INTO #ProjectLayerContentIDRecursionParam, #Type
END
-- close the cursor
CLOSE ProjectLayerContentChildren_Cursor
DEALLOCATE ProjectLayerContentChildren_Cursor
END