android sqlite 总结

private static class DatabaseHelper extends SQLiteOpenHelper {
DatabaseHelper(Context context) {
super(context, DB_NAME, null, DB_VERSION);
直到调用getWritableDatabase()函数或者getReadableDatabase()时才会创建或者打开数据库。（如果数据库没有创建，那么会先创建数据库）
Parameters
context to use to open or create the database
name of the database file, or null for an in-memory database
private static final int DB_VERSION = 2;
private static final String TABLE_NAME_1 = "MyOrder";
private static final String TABLE_NAME_2 = "OrderLine";
cur.moveToFirst();
public Cursor query(String table, String[] columns, String selection, String[] selectionArgs, String groupBy, String having, String orderBy)
+ " text" + ");");
db.execSQL("CREATE TABLE " + TABLE_NAME_2 + " (" + "order_no"
+ " text not null, " + "item_no" + " text not null, "
android.database.sqlite.SQLiteOpenHelperpublic SQLiteOpenHelper(Context context, String name, SQLiteDatabase.CursorFactory factory, int version) Create a helper object to create, open, and/or manage a database. The database is not actually created or opened until one of getWritableDatabase() or getReadableDatabase() is called.
try {
db.execSQL(sql_1);
db.execSQL(sql_2);
db.execSQL(sql_3);
setTitle("insert records ok!");
} catch (SQLException e) {
SQLiteOpenHelper，如果这个数据库存在，那么SQLiteOpenHelper负责管理数据库。
如果数据库不存在，那么SQLiteOpenHelper会建立一个数据库。
如果需要的话，升级数据库。
private static final String DB_NAME = "CartDB.db";
String sql = "create table Student(" + "stud_no text not null, "
+ "stud_name text );";
try {
db.execSQL(sql);
setTitle("create table ok!");
} catch (SQLException e) {
Log.e("ERROR", e.toString());
setTitle("create table Error!");
}
drop数据库：
mOpenHelper = new DatabaseHelper(v.getContext());
String sql_2 = "insert into Student (stud_no, stud_name) values('S201', 'Tom Kao');";
String sql_3 = "insert into Student (stud_no, stud_name) values('S333', 'Peter Rabbit');";
SQLiteDatabase db = mOpenHelper.getWritableDatabase();
String sql = "drop table Student";
try {
db.execSQL(sql);
setTitle("drop table ok!");
cur = db.query("Student", col, null, null, null, null, null);
Integer n = cur.getCount();
String ss = Integer.toString(n);
setTitle(ss + " records");
A helper class to manage database creation and version management.
SQLiteOpenHelper类是管理数据库生成和数据库版本建立的辅助类。
You create a subclass implementing onCreate(SQLiteDatabase), onUpgrade(SQLiteDatabase, int, int) and optionally onOpen(SQLiteDatabase), and this class takes care of opening the database if it exists, creating it if it does not, and upgrading it as necessary. Transactions are used to make sure the database is always in a sensible state
}
@Override
public void oபைடு நூலகம்Create(SQLiteDatabase db) {
db.execSQL("CREATE TABLE " + TABLE_NAME_1 + " (" + "order_no"
+ " text not null, " + "type" + " text not null, " + "desc"
} catch (SQLException e) {
Log.e("ERROR", e.toString());
setTitle("drop table Error!");
}
插入语句：
采用sql语句进行插入：
mOpenHelper = new DatabaseHelper(v.getContext());
Log.e("ERROR", e.toString());
}
采用第二种方便的方法进行插入：（采用contentValues的方法）
mOpenHelper = new DatabaseHelper(v.getContext());
SQLiteDatabase db = mOpenHelper.getWritableDatabase();
ContentValues cv = new ContentValues();
cv.put("stud_no", "S108");
cv.put("stud_name", "Lily Chen");
db.insert("Student", null, cv);
查询语句：
mOpenHelper = new DatabaseHelper(v.getContext());
SQLiteDatabase db = mOpenHelper.getReadableDatabase();
String col[] = { "stud_no", "stud_name" };
SQLiteDatabase db = mOpenHelper.getWritableDatabase();
String sql_1 = "insert into Student (stud_no, stud_name) values('S108', 'Lily Chen');";
cv.put("stud_no", "S333");
cv.put("stud_name", "Peter Rabbit");