Based on the Android sqliteopenhelper && CRUD usage _android

Copy Code code as follows:

public class DBOPenhelper extends Sqliteopenhelper {
Class is not instantiated and cannot be used as a parameter to a parent class constructor and must be declared static
Public Dbopenhelper (context, int version) {
Super (context, "sqlite.db", null, version);
The third parameter cursorfactory specifies the factory class that obtains a cursor instance when executing the query, set to NULL to represent the default cursor factory using the system;
}
@Override
public void onCreate(Sqlitedatabase db) {//The database was invoked the first time it was created, and the version number assigned at the beginning of the creation of the database is 0
Sqlitedatabase used to generate database tables; database storage path: <package name>/databases/
Db.execsql ("CREATE TABLE Person" (PersonID integer primary key autoincrement, name varchar (20));
}
@Override
public void Onupgrade(sqlitedatabase db, int oldversion, int newversion) {///when the version number is upgraded and not called if the database does not exist
Db.execsql ("ALTER TABLE person add phone varchar () NULL")//Add a column to the table
}
}
dbopenhelper dbopenhelper = new Dbopenhelper (GetContext (), 1);
Dbopenhelper.getwritabledatabase ()//will create database table Or/open database table

public classPersonservice{
PrivateDbopenhelperDbopenhelper;
Public Personservice {
Super ();
This.dbopenhelper = new Dbopenhelper (context, 2);
}
public void Save (person person) {
Sqlitedatabase db = Dbopenhelper.getwritabledatabase ();
Sqlitedatabase DB2 = Dbopenhelper.getwritabledatabase (); There is a caching function, the same helper uses this method to obtain the object is DB;
Db.execsql ("INSERT into person (Name,phone) VALUES (?,?)", new object[] {person.getname (), Person.getphone ()});
}
public void Delete (Integer id) {
Sqlitedatabase db = Dbopenhelper.getwritabledatabase ();
Db.execsql ("Delete from person where personid=?", new object[] {ID});
}
public void update (person person) {
Sqlitedatabase db = Dbopenhelper.getwritabledatabase ();
Db.execsql ("Update person set name=?,phone=?") Where personid=? ", new object[] {person.getname (), Person.getphone (), Person.getid ()});
}
Public person find (Integer ID) {
Sqlitedatabase db = Dbopenhelper.getreadabledatabase ();
If the database disk space is not full, the resulting instance isgetwritabledatabase ()The resulting object; Because this method invokes the Getwritabledatabase method;
Cursor Cursor = Db.rawquery ("select * from person where personid=?", new string[] {id.tostring ()});
if (Cursor.movetofirst ()) {
int PersonID = Cursor.getint (Cursor.getcolumnindex ("PersonID"));
String name = cursor.getstring (Cursor.getcolumnindex ("name"));
String phone = cursor.getstring (Cursor.getcolumnindex ("Phone"));
Return to new person (PersonID, name, phone);
}
Cursor.close ();
return null;
}
/*
* Get the paging data
*/
Public List getscolldata (int offest, int maxresult) {
List persons = new ArrayList ();
Sqlitedatabase db = Dbopenhelper.getreadabledatabase ();
Cursor Cursor = Db.rawquery ("SELECT * from person ' ORDER by PersonID ASC limit?,?", new string[] {string.valueof (offest), S Tring.valueof (Maxresult)});
while (Cursor.movetonext ()) {
int PersonID = Cursor.getint (Cursor.getcolumnindex ("PersonID"));
String name = cursor.getstring (Cursor.getcolumnindex ("name"));
String phone = cursor.getstring (Cursor.getcolumnindex ("Phone"));
Persons.add (New person (PersonID, name, phone));
}
Cursor.close ();
return persons;
}
Public long GetCount () {
Sqlitedatabase db = Dbopenhelper.getreadabledatabase ();
Cursor Cursor = Db.rawquery ("SELECT count (*) from person", NULL);
Cursor.movetofirst ();
Long result = Cursor.getlong (0);
return result;
}
}

public classOtherpersonservice{
PrivateDbopenhelperDbopenhelper;
Public Otherpersonservice {
Super ();
This.dbopenhelper = new Dbopenhelper (context, 2);
}
public void Save (person person) {
Sqlitedatabase db = Dbopenhelper.getwritabledatabase ();
contentvaluesvalues = new Contentvalues ();//Contentvalues value specifically for saving fields
Values.put ("Name", Person.getname ());
Values.put ("Phone", Person.getphone ());
Db.insert ("person", null, values); The third parameter is a field value, the second parameter is a null field, if the third argument is null
}
public void Delete (Integer id) {
Sqlitedatabase db = Dbopenhelper.getwritabledatabase ();
Db.delete ("Person", "personid=", new string[] {id.tostring ()});
}
public void update (person person) {
Sqlitedatabase db = Dbopenhelper.getwritabledatabase ();
Contentvalues values = new Contentvalues ();
Values.put ("Name", Person.getname ());
Values.put ("Phone", Person.getphone ());
Db.update ("person", Values, "personid=", new string[] {Person.getid (). toString ()});
}
Public person find (Integer ID) {
Sqlitedatabase db = Dbopenhelper.getreadabledatabase ();
Cursor Cursor = db.query ("person", NULL, "Personid=?", new string[] {id.tostring ()}, NULL, NULL, NULL);
if (Cursor.movetofirst ()) {
int PersonID = Cursor.getint (Cursor.getcolumnindex ("PersonID"));
String name = cursor.getstring (Cursor.getcolumnindex ("name"));
String phone = cursor.getstring (Cursor.getcolumnindex ("Phone"));
Return to new person (PersonID, name, phone);
}
Cursor.close ();
return null;
}
/*
* Get the paging data
*/
Public List getscolldata (int offest, int maxresult) {
List persons = new ArrayList ();
Sqlitedatabase db = Dbopenhelper.getreadabledatabase ();
Cursor Cursor = db.query ("person", NULL, NULL, NULL, NULL, NULL, "PersonID ASC", Offest + "," + Maxresult);
Db.query (table, columns, selection, Selectionargs, GroupBy, having, and limit);
while (Cursor.movetonext ()) {
int PersonID = Cursor.getint (Cursor.getcolumnindex ("PersonID"));
String name = cursor.getstring (Cursor.getcolumnindex ("name"));
String phone = cursor.getstring (Cursor.getcolumnindex ("Phone"));
Persons.add (New person (PersonID, name, phone));
}
Cursor.close ();
return persons;
}
Public long GetCount () {
Sqlitedatabase db = Dbopenhelper.getreadabledatabase ();
Cursor Cursor = db.query ("Person", new string[] {"Count (*)"}, NULL, NULL, NULL, NULL, NULL);
Db.query (table, columns, selection, Selectionargs, GroupBy, having, by);
Cursor.movetofirst ();
Long result = Cursor.getlong (0);
return result;
}
}