CHOIJEWON · Dec 4, 2025 · Dec 8, 2025 · Dec 8, 2025 · Apr 11, 2026
diff --git a/src/query-builder/InsertQueryBuilder.ts b/src/query-builder/InsertQueryBuilder.ts
@@ -812,7 +812,10 @@
                     !DriverUtils.isMySQLFamily(this.dataSource.driver) &&
                     !(this.dataSource.driver.options.type === "aurora-mysql") &&
                     !(
-                        this.dataSource.driver.options.type === "mssql" &&
+                        (this.dataSource.driver.options.type === "mssql" ||
+                            DriverUtils.isPostgresFamily(
+                                this.dataSource.driver,
+                            )) &&
                         this.isOverridingAutoIncrementBehavior(column)
                     )
                 )
@@ -1239,6 +1242,19 @@
         if (this.dataSource.driver.options.type === "mssql") {
             query += `;`
         }
+
+        // Inserting a specific value for an auto-increment primary key in mssql requires enabling IDENTITY_INSERT
+        // IDENTITY_INSERT can only be enabled for tables where there is an IDENTITY column and only if there is a value to be inserted (i.e. supplying DEFAULT is prohibited if IDENTITY_INSERT is enabled)
+        if (
+            this.connection.driver.options.type === "mssql" &&
+            this.expressionMap.mainAlias!.hasMetadata &&
+            columns.some((column) =>
+                this.isOverridingAutoIncrementBehavior(column),
+            )
+        ) {
+            query = `SET IDENTITY_INSERT ${tableName} ON; ${query}; SET IDENTITY_INSERT ${tableName} OFF`
+        }
+
         return query
     }
 
@@ -1247,10 +1263,44 @@
     *
     * @param mergeSourceAlias
     */
     protected createMergeIntoSourceExpression(
         mergeSourceAlias: string,
     ): string {
-        const columns = this.getInsertedColumns()
+        let columns = this.getInsertedColumns()
+
+        // For MERGE INTO, we need to include conflict path columns in the source
+        // even if they are auto-generated (e.g., identity columns in SAP HANA)
+        // because they are needed for the ON clause (conflict detection)
+        if (
+            this.expressionMap.onUpdate?.conflict &&
+            this.expressionMap.mainAlias!.hasMetadata
+        ) {
+            const conflictPaths = Array.isArray(
+                this.expressionMap.onUpdate.conflict,
+            )
+                ? this.expressionMap.onUpdate.conflict
+                : [this.expressionMap.onUpdate.conflict]
+
+            const conflictColumns =
+                this.expressionMap.mainAlias!.metadata.columns.filter(
+                    (column) =>
+                        conflictPaths.includes(column.databaseName) ||
+                        conflictPaths.includes(column.propertyPath),
+                )
+
+            // Add conflict columns that are not already in the inserted columns
+            const additionalColumns = conflictColumns.filter(
+                (conflictColumn) =>
+                    !columns.some(
+                        (col) =>
+                            col.databaseName === conflictColumn.databaseName,
+                    ),
+            )
+
+            if (additionalColumns.length > 0) {
+                columns = [...columns, ...additionalColumns]
+            }
+        }
 
         let expression = "USING ("
 
@@ -1430,7 +1480,9 @@
                     (column.isGenerated &&
                         column.generationStrategy === "uuid" &&
                         this.dataSource.driver.isUUIDGenerationSupported()) ||
-                    (column.isGenerated && column.generationStrategy !== "uuid")
+                    (column.isGenerated &&
+                        column.generationStrategy !== "uuid" &&
+                        !this.isOverridingAutoIncrementBehavior(column))
                 ) {
                     expression += `DEFAULT`
                 } else {

diff --git a/test/functional/repository/basic-methods/repository-basic-methods.test.ts b/test/functional/repository/basic-methods/repository-basic-methods.test.ts
@@ -911,6 +911,35 @@ describe("repository > basic methods", () => {
                         .should.be.rejectedWith(TypeORMError)
                 }),
             ))
+        it("should upsert with primary key as conflict path", () =>
+            Promise.all(
+                connections.map(async (connection) => {
+                    if (!connection.driver.supportedUpsertTypes.length) return
+
+                    const postRepository = connection.getRepository(Post)
+
+                    // First upsert - should insert a new post with id=1
+                    await postRepository.upsert(
+                        { id: 1, title: "Upserted post" },
+                        { conflictPaths: ["id"] },
+                    )
+
+                    // Second upsert - should update the existing post with id=1
+                    await postRepository.upsert(
+                        { id: 1, title: "Upserted post2" },
+                        { conflictPaths: ["id"] },
+                    )
+
+                    // Verify only one post exists with the updated title
+                    const posts = await postRepository.find()
+                    posts.length.should.be.equal(
+                        1,
+                        "Should have only one post, not duplicate",
+                    )
+                    posts[0].id!.should.be.equal(1)
+                    posts[0].title.should.be.equal("Upserted post2")
+                }),
+            ))
     })
 
     describe("preload also should also implement merge functionality", function () {