android room database returns wrong schema table

Question

I have a database migration issue

Use: Kotlin, Room

I want to upgrade database from 1 to 3
I already succeeded migration from 1 to 2 and from 2 to 3 perfectly.

But, when I try to upgrade from 1 to 3, in 3 migration result of query returns version 1's schema.

version 1 :
Account Table
Column: address, type, id, memo

version 2:
Account Table
Column: address, type, path, memo

version 3:
Account Table
Column: address, type, path, memo, order

private val MIGRATION_1_2: Migration = object : Migration(1, 2) {
override fun migrate(database: SupportSQLiteDatabase) {
    database.beginTransaction()

    try {
    database.execSQL("""
            CREATE TABLE Account_tmp (
            address TEXT NOT NULL, type TEXT, path TEXT, memo TEXT, 
            PRIMARY KEY(address))""")

        database.query("SELECT * FROM Account").use { cursor ->
            if (cursor != null && cursor.count > 0) {
                while (cursor.moveToNext()) {
                    val address = cursor.getString(cursor.getColumnIndex("address"))
                    val type = cursor.getString(cursor.getColumnIndex("type"))
                    val path = "Id:" + cursor.getInt(cursor.getColumnIndex("id"))
                    val memo = cursor.getInt(cursor.getColumnIndex("memo"))

                    val values = ContentValues()
                    values.put("address", address)
                    values.put("type", type)
                    values.put("path", path)
                    values.put("memo", memo)
                    database.insert("Account_tmp", SQLiteDatabase.CONFLICT_FAIL, values)
                }
            }
        }
        database.execSQL("DROP TABLE IF EXISTS Account")
        database.execSQL("ALTER TABLE Account_tmp RENAME TO Account")

        database.setTransactionSuccessful()
    } finally {
        database.endTransaction()
    }
}


private val MIGRATION_2_3: Migration = object : Migration(2, 3) {
override fun migrate(database: SupportSQLiteDatabase) {
    database.beginTransaction()

    try {
    database.execSQL("""
            CREATE TABLE Account_tmp (
            address TEXT NOT NULL, type TEXT, path TEXT, memo TEXT, order TEXT,
            PRIMARY KEY(address))""")

        database.query("SELECT * FROM Account").use { cursor ->
            if (cursor != null && cursor.count > 0) {
                while (cursor.moveToNext()) {
                    val address = cursor.getString(cursor.getColumnIndex("address"))
                    val type = cursor.getString(cursor.getColumnIndex("type"))
                    val path = cursor.getString(cursor.getColumnIndex("path")) ************************  // getting error -> because table hasn't path column
                    val memo = cursor.getInt(cursor.getColumnIndex("memo"))

                    val values = ContentValues()
                    values.put("address", address)
                    values.put("type", type)
                    values.put("path", path)
                    values.put("memo", memo)
                    database.insert("Account_tmp", SQLiteDatabase.CONFLICT_FAIL, values)
                }
            }
        }
        database.execSQL("DROP TABLE IF EXISTS Account")
        database.execSQL("ALTER TABLE Account_tmp RENAME TO Account")

        database.setTransactionSuccessful()
    } finally {
        database.endTransaction()
    }
}

When i try to upgrade db from 1 to 3, exception occurs in MIGRATION_2_3
And when I'm debugging, querying result is awkward....

private val MIGRATION_1_2: Migration = object : Migration(1, 2) {
override fun migrate(database: SupportSQLiteDatabase) {
    database.beginTransaction()

    try {
    database.execSQL("""
            CREATE TABLE Account_tmp (
            address TEXT NOT NULL, type TEXT, path TEXT, memo TEXT, 
            PRIMARY KEY(address))""")

        database.query("SELECT * FROM Account").use { cursor ->
            if (cursor != null && cursor.count > 0) {
                while (cursor.moveToNext()) {
                    val address = cursor.getString(cursor.getColumnIndex("address"))
                    val type = cursor.getString(cursor.getColumnIndex("type"))
                    val path = "Id:" + cursor.getInt(cursor.getColumnIndex("id"))
                    val memo = cursor.getInt(cursor.getColumnIndex("memo"))

                    val values = ContentValues()
                    values.put("address", address)
                    values.put("type", type)
                    values.put("path", path)
                    values.put("memo", memo)
                    database.insert("Account_tmp", SQLiteDatabase.CONFLICT_FAIL, values)
                }
            }
        }
        database.execSQL("DROP TABLE IF EXISTS Account")
        database.execSQL("ALTER TABLE Account_tmp RENAME TO Account")

        database.setTransactionSuccessful()
    } finally {
        database.endTransaction()

        // database.query("SELECT * FROM Account") have {address, type, id, memo} (ver 1 schema) ****** -> why??
    }
}
private val MIGRATION_2_3: Migration = object : Migration(2, 3) {
override fun migrate(database: SupportSQLiteDatabase) {
    database.beginTransaction()

    try {
    database.execSQL("""
            CREATE TABLE Account_tmp (
            address TEXT NOT NULL, type TEXT, path TEXT, memo TEXT, order TEXT,
            PRIMARY KEY(address))""")

        database.query("SELECT * FROM Account").use { cursor ->
            if (cursor != null && cursor.count > 0) {
                while (cursor.moveToNext()) {
                    // cursor's column has {address, type, id, memo} (ver 1 schema), not (address, type, path, memo)(ver 2 schema) -> why??
                    val address = cursor.getString(cursor.getColumnIndex("address"))
                    val type = cursor.getString(cursor.getColumnIndex("type"))
                    val path = cursor.getString(cursor.getColumnIndex("path")) // exception because account table has not path.. still has id column
                    val memo = cursor.getInt(cursor.getColumnIndex("memo"))

                    val values = ContentValues()
                    values.put("address", address)
                    values.put("type", type)
                    values.put("path", path)
                    values.put("memo", memo)
                    database.insert("Account_tmp", SQLiteDatabase.CONFLICT_FAIL, values)
                }
            }
        }
        database.execSQL("DROP TABLE IF EXISTS Account")
        database.execSQL("ALTER TABLE Account_tmp RENAME TO Account")

        database.setTransactionSuccessful()
    } finally {
        database.endTransaction()
    }
}

I don't no why database.query("SELECT * FROM Account") returns wrong db schema........

even, if I add meaningless query below rename to query, then I can migration successfully from 1 to 3 version

private val MIGRATION_1_2: Migration = object : Migration(1, 2) {
override fun migrate(database: SupportSQLiteDatabase) {
    database.beginTransaction()

    try {
    database.execSQL("""
            CREATE TABLE Account_tmp (
            address TEXT NOT NULL, type TEXT, path TEXT, memo TEXT, 
            PRIMARY KEY(address))""")

        database.query("SELECT * FROM Account").use { cursor ->
            if (cursor != null && cursor.count > 0) {
                while (cursor.moveToNext()) {
                    val address = cursor.getString(cursor.getColumnIndex("address"))
                    val type = cursor.getString(cursor.getColumnIndex("type"))
                    val path = "Id:" + cursor.getInt(cursor.getColumnIndex("id"))
                    val memo = cursor.getInt(cursor.getColumnIndex("memo"))

                    val values = ContentValues()
                    values.put("address", address)
                    values.put("type", type)
                    values.put("path", path)
                    values.put("memo", memo)
                    database.insert("Account_tmp", SQLiteDatabase.CONFLICT_FAIL, values)
                }
            }
        }
        database.execSQL("DROP TABLE IF EXISTS Account")
        database.execSQL("ALTER TABLE Account_tmp RENAME TO Account")

        database.query("SELECT * FROM Account").use { cursor ->
                 Log.e(TAG, "MIGRATION_1_2, account size=${cursor.count}")
                 // If I add this code, Migration from 1 to 3 success!!!!
        }


        database.setTransactionSuccessful()
    } finally {
        database.endTransaction()
    }
}

WHY??????????????????
I want to know why!!!!

Please help me
Here is my database code

companion object {

    private const val TAG = "TestDatabase"

    @Volatile
    private var instance: TestDatabase? = null

    fun getInstance(context: Context): TestDatabase =
            instance ?: synchronized(this) {
                instance
                        ?: buildDatabase(context).also { instance = it }
            }

    private fun buildDatabase(context: Context) =
            Room.databaseBuilder(context, TestDatabase::class.java, "test_database.db")
                    .allowMainThreadQueries()
                    .addMigrations(MIGRATION_1_2)
                    .addMigrations(MIGRATION_2_3)
                    .build()

    private val MIGRATION_1_2: Migration = object : Migration(1, 2) {
        ...
    }
    private val MIGRATION_2_3: Migration = object : Migration(2, 3) {
        ...
    }
}

Answer 1

I believe that your issue is that you are using a keyword ie order for the column name being added in MIGRATION_2_3 .

The log would have contained something similar to :-

2019-12-10 20:55:51.508 27554-27554/a.so59253634migrationschemanotchanging E/AndroidRuntime: FATAL EXCEPTION: main
    Process: a.so59253634migrationschemanotchanging, PID: 27554
    java.lang.RuntimeException: Unable to start activity ComponentInfo{a.so59253634migrationschemanotchanging/a.so59253634migrationschemanotchanging.MainActivity}: android.database.sqlite.SQLiteException: near "order": syntax error (code 1 SQLITE_ERROR): , while compiling: CREATE TABLE Account_tmp (
            address TEXT NOT NULL, type TEXT, path TEXT, memo TEXT, order TEXT,
            PRIMARY KEY(address))
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3270)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3409)
        at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:83)
        at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135)
        at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95)
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2016)
        at android.os.Handler.dispatchMessage(Handler.java:107)
        at android.os.Looper.loop(Looper.java:214)
        at android.app.ActivityThread.main(ActivityThread.java:7356)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:492)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:930)
     Caused by: android.database.sqlite.SQLiteException: near "order": syntax error (code 1 SQLITE_ERROR): , while compiling: CREATE TABLE Account_tmp (
            address TEXT NOT NULL, type TEXT, path TEXT, memo TEXT, order TEXT,
            PRIMARY KEY(address))
        at android.database.sqlite.SQLiteConnection.nativePrepareStatement(Native Method)
        at android.database.sqlite.SQLiteConnection.acquirePreparedStatement(SQLiteConnection.java:986)
        at android.database.sqlite.SQLiteConnection.prepare(SQLiteConnection.java:593)
        at android.database.sqlite.SQLiteSession.prepare(SQLiteSession.java:590)
        at android.database.sqlite.SQLiteProgram.<init>(SQLiteProgram.java:61)
        at android.database.sqlite.SQLiteStatement.<init>(SQLiteStatement.java:33)
        at android.database.sqlite.SQLiteDatabase.executeSql(SQLiteDatabase.java:1805)
        at android.database.sqlite.SQLiteDatabase.execSQL(SQLiteDatabase.java:1733)
        at androidx.sqlite.db.framework.FrameworkSQLiteDatabase.execSQL(FrameworkSQLiteDatabase.java:242)
        at a.so59253634migrationschemanotchanging.TestDatabase$Companion$MIGRATION_2_3$1.migrate(AppDatabase.kt:80)

You could use

`order`

or not use the order keyword for the column's name.

eg :-

    private val MIGRATION_2_3: Migration = object : Migration(2, 3) {
        override fun migrate(database: SupportSQLiteDatabase) {
            database.beginTransaction()

            try {
                database.execSQL(
                    """
    CREATE TABLE Account_tmp (
    address TEXT NOT NULL, type TEXT, path TEXT, memo TEXT, `order` TEXT,
    PRIMARY KEY(address))"""
                )

                database.query("SELECT * FROM Account").use { cursor ->
                    if (cursor != null && cursor.count > 0) {
                        while (cursor.moveToNext()) {
                            // cursor's column has {address, type, id, memo} (ver 1 schema), not (address, type, path, memo)(ver 2 schema) -> why??
                            val address = cursor.getString(cursor.getColumnIndex("address"))
                            val type = cursor.getString(cursor.getColumnIndex("type"))
                            val path =
                                cursor.getString(cursor.getColumnIndex("path")) // exception because account table has not path.. still has id column
                            val memo = cursor.getInt(cursor.getColumnIndex("memo"))

                            val values = ContentValues()
                            values.put("address", address)
                            values.put("type", type)
                            values.put("path", path)
                            values.put("memo", memo)
                            database.insert(
                                "Account_tmp",
                                SQLiteDatabase.CONFLICT_FAIL,
                                values
                            )
                        }
                    }
                }
                database.execSQL("DROP TABLE IF EXISTS Account")
                database.execSQL("ALTER TABLE Account_tmp RENAME TO Account")

                database.setTransactionSuccessful()
            } finally {
                database.endTransaction()
            }
        }
    }