Android SQLite Data Storage

SQLite is a lightweight database. It is used on android. A database file represents a database. The SQL syntax is basically the same as that of mysql. The expressions are different.

Obtain the SQLiteDatabase object

SQLiteDatabase Method

Static SQLiteDatabaseOpenDatabase (String path, SQLiteDatabase. CursorFactory factory, int flags)

E: SQLiteDatabase db = SQLiteDatabase. openDatabase (path, factory, flags); // open the path file represented by path

Static SQLiteDatabaseOpenOrCreateDatabase (File file, SQLiteDatabase. CursorFactory factory)

E: SQLiteDatabase db = SQLiteDatabase. openOrCreateDatabase (mFile, factory); // open the database file corresponding to the mFile. If the file does not exist, create

Static SQLiteDatabaseOpenOrCreateDatabase (String path, SQLiteDatabase. CursorFactory factory );

E: SQLiteDatabase db = SQLiteDatabase. openOrCreateDatabaes (mPath, factory); // open the database file corresponding to mPath. If the file does not exist, create

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SQLiteDatabase provides several methods to operate databases

ExecSQL (String SQL, Object [] objs); // Execute SQL statements with placeholders

ExexSQL (String SQL );// Directly execute the SQL statement

Insert (String table_name, String nullColumn, ContentValues values); // execute the SQL insert statement

Delete (String table_name, String where, String [] whereArgs); // delete

Update (String table_name, ContentValues values, String where, String [] whereArgs); // update

 

For example:

Name	Age
Admin	20

 

Db.exe cSQL ("select * from table_name where id>? ", New int [] {10 });//? It indicates a placeholder. The placeholder must be of the same type and sequence as the following array.

Db.exe cSQL ("select * from table_name where id> 10") // similar to the first sentence, execute select * from table_name where id> 10 in a mysql statement;

It seems that only execSQL (xc) is used. This statement basically solves all the needs... add, delete, modify, and query...

 

 

ContentValues values = new ContentValues ();

Values. put ("name", "admin ");

Values. put ("age", "20"); // values. put (columnName, value) ;=> Map. put (key, value );

Db. insert (table_name, null, values); // insert records in the table_name Table, column name = value admin age = 20

// Equivalent to insert into table_name (name, age) values ("admin", 20 );

　

 

Db. delete ("table_name", "name like", new String [] {"a % "}); // delete a row whose name column value starts with a record ==> delete table_name where name like "a % ";

 

Values. put ("age", "25 ");

Db. update ("table_name", values, "age =", new String [] ("20"); // update the record whose age is 20, the modified value is placed in values ==> update table_name set age = 25 where age = 20;