simple sqlite example? [duplicate]_问答_开发者

This question already has an answer here: Closed 11 years ago.

Possible Duplicate:
sqlite example program in android

Hi I'm new to android and I am having some trouble finding a good tutorial for an SQLite database. What I wanted to do was to 开发者_高级运维store a line of data in the database, reference it later and then delete it once its been referenced. As I have said I am new to this sort of thing and have no clue even what any of the syntax is so if there is a simple tutorial out there I would like to know.

try this

try { // creating a database called db and a Table inside it, called
            // userdetails. With username and password as columns.

        db = openOrCreateDatabase("UserDetails.db",
                Context.MODE_PRIVATE, null); // optional CursorFactory
        db.execSQL("drop table if exists userdetails");
        db.execSQL("create table userdetails " + " ( username TEXT,"
                + "password TEXT);");

    } catch (SQLException x) {
        x.printStackTrace();
        Log.e(LOG_TAG_NAME, "Database creation error");

    }

//.........................................................................
    // and insert values into the database table.
    try {
        db.execSQL("INSERT INTO " + "userdetails"
                + " (username,password)" + " VALUES ('hi','hello');");
        db.execSQL("INSERT INTO " + "userdetails"
                + " (username,password)" + " VALUES ('chris','gayle');");
        db.execSQL("INSERT INTO " + "userdetails"
                + " (username,password)" + " VALUES ('v','v');");
    } catch (Exception e) {
        e.printStackTrace();
        Log.e(LOG_TAG_NAME, "inserting table values error");
    }
    String[] columns = { "username", "password" };
    Cursor c = db.query("userdetails", columns, null, null, null, null,
            null);

now use the cursor to retrieve values

also have a look at

http://developer.android.com/guide/topics/data/data-storage.html#db

hope all this helps

EZ Answer I think.

If I understand your needs I think that you will find a database is overkill. You can do this a lot easier I think with just a few lines of code. If I am correct, a "line of data" sounds like a single String that you want to persist. If that is the case SharedPreferneces is by far your best bet for easy implementation.

Check out THIS link to the Dev-Guide's Shared Preferences Data Storage section

Its as easy as initializing the Preferences, and either putting or asking for a value by key.

On the other hand if you need to store many lines of relational data, search through them, sort them, etc. then a database is what you want.

Generally, I choose the data storage mechanism based on what is being stored and how i want to retrieve it:

Single primitives (and Strings) get stored best in SharedPreferences. This is a fast and easy implementation. You can get away with storing a couple of values if you need to to represent a more complex class. Sometimes it makes sense to create a helper class that keeps track of complex schemes.
Serializable complex data, like parameterized Collections, that are loaded into memory all at once, long streams of text to be parsed, or if that data is a byte stream it gets stored to a file. This is not as fast and involves catching a lot of potential IO issues. But most objects are serializable or easily made that way.
Tables of data that I want to query or provide a Cursor for because of how long they are go into a database. The start up and resource expenses of a database are huge. Writing all the helper code to use them is a pain in the extreme.