First pass at handling existing data and duplicates

util/Migrator/DbScripts/2025-12-20_00_Collection_AddDefaultCollectionOwnerAndConstraint.sql

@@ -1,4 +1,4 @@
--- TODO! Handle existing data in MSSQL (and EF if releasing before this). This assumes the column is populated, if it isn't then it'll create at least 1 duplicate.
+-- TODO! Handle existing data in EF if releasing before this. This assumes the column is populated, if it isn't then it'll create at least 1 duplicate.
 -- Add DefaultCollectionOwnerId column to Collection table for Type=1 collections
 -- This enables a filtered unique constraint to prevent duplicate default collections
 
@@ -15,6 +15,65 @@ BEGIN
 END
 GO
 
+-- Populate DefaultCollectionOwnerId for existing Type=1 collections
+-- Find the OrganizationUser with Manage permissions on each default collection
+IF EXISTS (
+    SELECT *
+    FROM INFORMATION_SCHEMA.COLUMNS
+    WHERE TABLE_SCHEMA = 'dbo'
+      AND TABLE_NAME = 'Collection'
+      AND COLUMN_NAME = 'DefaultCollectionOwnerId'
+)
+BEGIN
+    UPDATE c
+    SET c.[DefaultCollectionOwnerId] = cu.[OrganizationUserId]
+    FROM [dbo].[Collection] c
+    INNER JOIN [dbo].[CollectionUser] cu ON c.[Id] = cu.[CollectionId]
+    WHERE c.[Type] = 1
+      AND cu.[Manage] = 1
+      AND c.[DefaultCollectionOwnerId] IS NULL
+END
+GO
+
+-- Handle duplicate default collections for the same user/organization
+-- Convert duplicates to SharedCollections (Type=0), keeping the oldest one
+IF EXISTS (
+    SELECT *
+    FROM INFORMATION_SCHEMA.COLUMNS
+    WHERE TABLE_SCHEMA = 'dbo'
+      AND TABLE_NAME = 'Collection'
+      AND COLUMN_NAME = 'DefaultCollectionOwnerId'
+)
+BEGIN
+    DECLARE @UtcNow DATETIME2(7) = GETUTCDATE();
+
+    -- Find duplicate default collections (same OrganizationUserId + OrganizationId + Type=1)
+    -- Keep the oldest one, convert the rest to SharedCollections
+    WITH DuplicateCollections AS (
+        SELECT
+            c.[Id],
+            c.[OrganizationId],
+            c.[DefaultCollectionOwnerId],
+            c.[CreationDate],
+            ROW_NUMBER() OVER (
+                PARTITION BY c.[DefaultCollectionOwnerId], c.[OrganizationId]
+                ORDER BY c.[CreationDate] ASC
+            ) AS RowNum
+        FROM [dbo].[Collection] c
+        WHERE c.[Type] = 1
+          AND c.[DefaultCollectionOwnerId] IS NOT NULL
+    )
+    UPDATE c
+    SET
+        c.[Type] = 0,  -- Convert to SharedCollection
+        c.[DefaultCollectionOwnerId] = NULL,
+        c.[RevisionDate] = @UtcNow
+    FROM [dbo].[Collection] c
+    INNER JOIN DuplicateCollections dc ON c.[Id] = dc.[Id]
+    WHERE dc.RowNum > 1  -- Keep only the first (oldest) collection
+END
+GO
+
 -- Add foreign key constraint to OrganizationUser
 IF NOT EXISTS (
     SELECT *