Android 中的数据库操作

 

1创建数据库

继承SQLiteOpenHelper(抽象类) 。实现一下两个方法

abstract void	onCreate(SQLiteDatabase db) Called when the database is created for the first time.
abstract void	onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) Called when the database needs to be upgraded.

 

2 数据的操作。（增删改查）

synchronized SQLiteDatabase	getReadableDatabase() Create and/or open a database.
synchronized SQLiteDatabase	getWritableDatabase() Create and/or open a database that will be used for reading and writing.

获得可读或可写的数据库。

通过 SQLiteDatabase 类进行数据操作。

常用方法如下：

void	close() Close the database.
int	delete(String table, String whereClause, String[] whereArgs) Convenience method for deleting rows in the database.
void	execSQL(String sql) Execute a single SQL statement that is NOT a SELECT or any other SQL statement that returns data.
void	execSQL(String sql, Object[] bindArgs) Execute a single SQL statement that is NOT a SELECT/INSERT/UPDATE/DELETE.
long	insert(String table, String nullColumnHack, ContentValues values) Convenience method for inserting a row into the database.
long	insertOrThrow(String table, String nullColumnHack, ContentValues values) Convenience method for inserting a row into the database.
boolean	isOpen()
boolean	isReadOnly() return whether the DB is opened as read only.
static SQLiteDatabase	openDatabase(String path, SQLiteDatabase.CursorFactory factory, int flags, DatabaseErrorHandler errorHandler) Open the database according to the flags OPEN_READWRITE OPEN_READONLY CREATE_IF_NECESSARY and/or NO_LOCALIZED_COLLATORS.
static SQLiteDatabase	openDatabase(String path, SQLiteDatabase.CursorFactory factory, int flags) Open the database according to the flags OPEN_READWRITE OPEN_READONLY CREATE_IF_NECESSARY and/or NO_LOCALIZED_COLLATORS.
static SQLiteDatabase	openOrCreateDatabase(String path, SQLiteDatabase.CursorFactory factory, DatabaseErrorHandler errorHandler) Equivalent to openDatabase(path, factory, CREATE_IF_NECESSARY, errorHandler).
static SQLiteDatabase	openOrCreateDatabase(String path, SQLiteDatabase.CursorFactory factory) Equivalent to openDatabase(path, factory, CREATE_IF_NECESSARY).
static SQLiteDatabase	openOrCreateDatabase(File file, SQLiteDatabase.CursorFactory factory) Equivalent to openDatabase(file.getPath(), factory, CREATE_IF_NECESSARY).
Cursor	query(String table, String[] columns, String selection, String[] selectionArgs, String groupBy, String having, String orderBy, String limit) Query the given table, returning a Cursor over the result set.
Cursor	query(String table, String[] columns, String selection, String[] selectionArgs, String groupBy, String having, String orderBy) Query the given table, returning a Cursor over the result set.
Cursor	query(boolean distinct, String table, String[] columns, String selection, String[] selectionArgs, String groupBy, String having, String orderBy, String limit) Query the given URL, returning a Cursor over the result set.
Cursor	queryWithFactory(SQLiteDatabase.CursorFactory cursorFactory, boolean distinct, String table, String[] columns, String selection, String[] selectionArgs, String groupBy, String having, String orderBy, String limit) Query the given URL, returning a Cursor over the result set.
Cursor	rawQuery(String sql, String[] selectionArgs) Runs the provided SQL and returns a Cursor over the result set.
Cursor	rawQueryWithFactory(SQLiteDatabase.CursorFactory cursorFactory, String sql, String[] selectionArgs, String editTable) Runs the provided SQL and returns a cursor over the result set.
static int	releaseMemory() Attempts to release memory that SQLite holds but does not require to operate properly.
long	replace(String table, String nullColumnHack, ContentValues initialValues) Convenience method for replacing a row in the database.
long	replaceOrThrow(String table, String nullColumnHack, ContentValues initialValues) Convenience method for replacing a row in the database.