Android sqlite database how to#
Android sqlite database upgrade#
Android sqlite database android#

Next, let us use examples to more intuitively experience the usage of SQLiteOpenHelper. At this time, the overridden onCreate() method will also be executed, so it is usually here to deal with some of the logic of creating a table. Build out After the instance of SQLiteOpenHelper, call its getReadableDatabase() or getWritableDatabase() method Then the database can be created, and the database files will be stored in the /data/data//databases/ directory.

Android sqlite database upgrade#

The fourth parameter represents the version number of the current database, which can be used to upgrade the database. The third parameter allows us to return a custom Cursor when querying data, usually null is passed in. The second parameter is the database name, the name specified here is used when creating the database Weighed. This construction method receives four parameters, the first parameter is Context, there is nothing to say about this, it must have It can operate on the database.

There are two construction methods in SQLiteOpenHelper that can be rewritten, generally the construction method with fewer parameters is used can.

Do not The same is that when the database is not writable (such as the disk space is full) the pair returned by the getReadableDatabase() method The image will open the database in read-only mode, and the getWritableDatabase() method will be abnormal. Both methods can create or open an existing database (if the database already exists Open directly, otherwise create a new database), and return an object that can read and write to the database. There are two very important instance methods in SQLiteOpenHelper, getReadableDatabase() and getWritableDatabase(). There are two abstract methods in SQLiteOpenHelper, namely onCreate() and onUpgrade(), we must rewrite these two methods in our own helper class, and then in these two In this method, the logic of creating and upgrading the database is realized. First of all, you need to know that SQLiteOpenHelper is an abstract class, which means that if we want to use it, You need to create your own helper class to inherit it. Since there are good things that can be used directly, Then we naturally have to try it, and I will introduce the basic usage of SQLiteOpenHelper below. The helper class, with the help of this class, the database can be created and upgraded very simply.

Android sqlite database android#

In order for us to manage the database more conveniently, Android provides an SQLiteOpenHelper helper.

Android sqlite database how to#

So letвЂ™s quickly take a look at how to use SQLite database in Android Studio.Д¬reate SQLite database in Android Studio: ItвЂ™s hard to imagine how to use files or SharedPreferences to store these large amounts of data and complex structure data? But you can do it with a database To. Content and most conversations may also correspond to a contact in the phone book. When you need to store a large amount of complex relational data, For example, there may be many conversations in the SMS program of our mobile phone, and each conversation contains many pieces of information. Android embeds this extremely powerful database into In the system, the local persistence function has made a qualitative leap. And SQLite is much simpler than ordinary databases, it is very It can be used without setting a user name and password. SQLite database Not only supports standard SQL syntax but also follows the ACID transaction of the database, so as long as you have used other With relational databases, you can quickly get started with SQLite database. SQLite database is a lightweight relational database, its computing speed is very fast, It occupies very little resources, usually, only a few hundred K of memory is enough, so it is especially suitable for use on mobile devices. Sqlite Database in Android Studio Creating CRUD System: in this article, I am going to show how to create and connect SQLite database in android.

deleting data from the SQLite database in Android Studio:.

updating data using SQLite database in Android Studio:.

adding data using SQLite database in Android Studio:.

CRUD system using SQLite database in Android studio:.

Upgrade SQLite Database in Android Studio:.

Create SQLite database in Android Studio:.