fix: resolves issue with mssql column recreation when length max is i…

…n lower case

Closes: typeorm#9399

src/driver/sqlserver/SqlServerDriver.ts

@@ -1035,7 +1035,10 @@ export class SqlServerDriver implements Driver {
         // of data type precedence to the expressions specified in the formula.
         if (columnMetadata.asExpression) return false
 
-        return tableColumn.length !== this.getColumnLength(columnMetadata)
+        return (
+            tableColumn.length?.toUpperCase() !==
+            this.getColumnLength(columnMetadata)?.toUpperCase()
+        )
     }
 
     protected lowerDefaultValueIfNecessary(value: string | undefined) {

test/github-issues/9399/entity/ExampleEntity.ts

@@ -0,0 +1,13 @@
+import { Entity, Generated } from "../../../../src"
+import { PrimaryGeneratedColumn } from "../../../../src"
+import { Column } from "../../../../src"
+
+@Entity()
+export class ExampleEntity {
+    @Generated("increment")
+    @PrimaryGeneratedColumn()
+    id: number
+
+    @Column({ type: "nvarchar", length: "max" })
+    value: string
+}

test/github-issues/9399/issue-9399.ts

@@ -0,0 +1,35 @@
+import "reflect-metadata"
+import {
+    createTestingConnections,
+    closeTestingConnections,
+} from "../../utils/test-utils"
+import { DataSource } from "../../../src"
+import { expect } from "chai"
+
+describe("github issues > #9399 mssql: Column is dropped and recreated in every migration", () => {
+    let dataSources: DataSource[]
+    before(
+        async () =>
+            (dataSources = await createTestingConnections({
+                entities: [__dirname + "/entity/*{.js,.ts}"],
+                schemaCreate: true,
+                dropSchema: true,
+                enabledDrivers: ["mssql"],
+            })),
+    )
+    after(() => closeTestingConnections(dataSources))
+
+    it("No migration should be created", () =>
+        Promise.all(
+            dataSources.map(async (dataSource) => {
+                await dataSource.runMigrations()
+                const sqlInMemory = await dataSource.driver
+                    .createSchemaBuilder()
+                    .log()
+
+                expect(sqlInMemory.upQueries).to.eql([])
+                expect(sqlInMemory.downQueries).to.eql([])
+            }),
+        ))
+    // you can add additional tests if needed
+})