Write SQL Statement Operations Database (MU-class SQLite notes)

One of the commonly used Android data storage methods SQLite study and operation notes

0. Video address: http://www.imooc.com/video/3382

1. Each program has its own database. By default, they do not interfere with each other.

1) Create a database and open it;

SQLiteDatabase db = openOrCreateDatabase ("user.db", MODE_PRIVATE, null);
2) The use of cursor cursor is equivalent to a collection of stored results, which can be understood as a list;

3) The cursor must be released after the end.

2. Specific code:

 1 public class MainActivity extends Activity {
 2 
 3 @Override
 4 protected void onCreate (Bundle savedInstanceState) {
 5 super.onCreate (savedInstanceState);
 6 setContentView (R.layout.activity_main);
 7
 8 // Each program has its own database. By default, they do not interfere with each other.
 9 // 1. Create a database and open
10 SQLiteDatabase db = openOrCreateDatabase ("user.db", MODE_PRIVATE, null);
11 db.execSQL ("create table if not exists usertb (_id integer primary key autoincrement," +
12 "name text not null, age integer not null, sex text not null)");
13 // Create user table including _id primary key, name, age, gender
14 db.execSQL ("insert into usertb (name, age, sex) values (‘ Zhang San ’,‘ Male ’, 26)");
15 db.execSQL ("insert into usertb (name, age, sex) values (‘ Liu Ming ’,‘ Male ’, 22)");
16 db.execSQL ("insert into usertb (name, age, sex) values (‘ Yu Si ’,‘ Female ’, 21)");
17
18 // 2. The use of cursor cursor is equivalent to storing a collection of results, which can be understood as a list
19 Cursor c = db.rawQuery ("select * from usertb", null);
20 if (c! = Null) {
21 while (c.moveToNext ()) {
22 Log.i ("info", "_ id:" + c.getInt (c.getColumnIndex ("_ id")));
23 Log.i ("info", "name:" + c.getString (c.getColumnIndex ("name")));
24 Log.i ("info", "sex:" + c.getString (c.getColumnIndex ("sex")));
25 Log.i ("info", "age:" + c.getInt (c.getColumnIndex ("age")));
26 Log.i ("info", "!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!" );
27}
28 c.close (); // 3. Release cursor
29}
30 db.close ();
31}
32}
View Code
3. Operation result:

4. Knowledge points:

1) You can use the tool navicat to open and view the db format file and view the user table created by yourself;

2) Cursor related:

 

Write SQL statements to operate the database (Mu Class SQLite notes)