您必须使用 INTEGER PRIMARY KEY 来得到一个自动增量列; INT 是远远不够的。

I have an app where i am trying to update a row in the Transactions table in my DB. Here's the table.

//table transactions column names
    public static final String C_ID = BaseColumns._ID; // special for id internally in system
    public static final String C_TYPE = "type";
    public static final String C_COMPANY_ID = "companyid";
    public static final String C_PERSON_ID = "person";
    public static final String C_NAME = "name";
    public static final String C_TAG_ID = "tagid";
    public static final String C_STATUS = "status";
    public static final String C_TAG_SCAN_TIME = "tagscantime";
    public static final String C_TAG_SENTSERVER_TIME = "tagsentservertime";
    public static final String C_TRANSACTIONS_LATITUDE = "transactionslatitude";
    public static final String C_TRANSACTIONS_LONGITUDE = "transactionslongitude";

.

When i insert a row into this table the column C_TAG_SENTSERVER_TIME is set to null. This is because i haven't at this point posted the transaction to the webservice. Once i get the response back from the server, i would like to update the row in the phone's DB with 'sent to server time'. At the moment i try to get the last row in the DB, i then try to get that row's id, that is the passed to the method that updates the row. Currently the result of

String[] param = {c.getString(c.getColumnIndex(LoginValidate.C_ID))};

is returnig null. Here's the rest of the update method. Why is the above call returning null?

public void updateTransactionWithServerTime(DateTime sentToServerAt) {

        SQLiteDatabase db = dbhelper.getWritableDatabase();

        Cursor c = null;

        c = db.query(DBHelper.TABLETRANSACTIONS, null, null, null, null, null, null);

        if (c != null ) {
            if  (c.moveToLast()) {
                String[] param = {c.getString(c.getColumnIndex(LoginValidate.C_ID))};
                Log.e(TAG, "C_ID = " + param[0]);
                ContentValues values = new ContentValues();
                  values.put(C_TAG_SENTSERVER_TIME, sentToServerAt.getMillis());

                 int res =  db.update(DBHelper.TABLETRANSACTIONS, values, LoginValidate.C_ID+"=?", param[0]);

                  Log.e(TAG, "done the update on trans table num of rows affected is " + res);

            }

         }
        c.close();
        db.close();
    }//end of updateTransactionWithServerTime

[edit1]

private class DBHelper extends SQLiteOpenHelper {

        // database name and version number
        public static final String DB_NAME = "carefreemobiledb.db";
        public static final int DB_VERSION = 26;

        //table names
        public static final String TABLETRANSACTIONS = "transactions";
        public static final String TABLECARER = "carer";
        public static final String TABLETRANSACTIONSMAP = "transactionsmap";
        public static final String TABLEPHONE = "phone";

        // public static final String C_ID = BaseColumns._ID; // special for id
        // internally in
        // system


        public DBHelper() {
            super(context, DB_NAME, null, DB_VERSION);
        }

        @Override
        public void onCreate(SQLiteDatabase db) {
            String sqlToCreateTransactionsTable = String
                    .format("create table %s ( %s INT primary key, %s TEXT, %s TEXT, %s TEXT, %s TEXT, %s TEXT," +
                            " %s TEXT, %s TEXT, %s INT, %s TEXT, %s TEXT )",
                            TABLETRANSACTIONS, C_ID, C_TYPE, C_COMPANY_ID, C_PERSON_ID,
                            C_NAME, C_TAG_ID, C_STATUS, C_TAG_SCAN_TIME, C_TAG_SENTSERVER_TIME,
                            C_TRANSACTIONS_LATITUDE, C_TRANSACTIONS_LONGITUDE);

            db.execSQL(sqlToCreateTransactionsTable);
            Log.e(TAG, "oncreate " + sqlToCreateTransactionsTable);

You must use INTEGER PRIMARY KEY to get an autoincrementing column; INT is not enough.