Add, delete, modify, and query SQLite Databases

Still, the code that is often repeated should be summarized.

1. First create a person instance:

Person. Java

package morgen.domain;public class Person {    private Integer id;    private String name;    private String phone;    public Integer getId() {        return id;    }    public void setId(Integer id) {        this.id = id;    }    public String getName() {        return name;    }    public void setName(String name) {        this.name = name;    }    public String getPhone() {        return phone;    }    public void setPhone(String phone) {        this.phone = phone;    }    public Person(Integer id, String name, String phone) {        this.id = id;        this.name = name;        this.phone = phone;    }    public Person(String name, String phone) {        this.name = name;        this.phone = phone;    }    @Override    public String toString() {        return "Person [id=" + id + ", name=" + name + ", phone=" + phone + "]";    }    }

2. Create Database Files and tables.

Dbopenhelper. Java

package morgen.db;import android.content.Context;import android.database.sqlite.SQLiteDatabase;import android.database.sqlite.SQLiteOpenHelper;public class DBOpenHelper extends SQLiteOpenHelper {    public DBOpenHelper(Context context) {        super(context, "morgen.db", null, 2);    }    @Override    public void onCreate(SQLiteDatabase db) {        db.execSQL("CREATE TABLE person(id integer primary key autoincrement, name varchar(20))");    }    @Override    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {        db.execSQL("ALTER TABLE person ADD phone VARCHAR(12) NULL");    }}

3. Operate the database

Personservice. Java

Package Morgen. service; import Java. util. arraylist; import Java. util. list; import android. content. context; import android. database. cursor; import android. database. SQLite. sqlitedatabase; import Morgen. DB. dbopenhelper; import Morgen. domain. person; public class personservice {private dbopenhelper; Public personservice (context) {dbopenhelper = new dbopenhelper (context);}/*** save data * @ Pa Ram person */Public void save (person) {sqlitedatabase DB = dbopenhelper. getwritabledatabase (); db.exe csql ("insert into person (name, phone) values (?,?) ", New object [] {person. getname (), person. getphone ()}); // dB. close ();}/*** Delete record * @ Param ID Record ID */Public void Delete (integer ID) {sqlitedatabase DB = dbopenhelper. getwritabledatabase (); db.exe csql ("delete from person where id =? ", New object [] {ID});}/*** update record * @ Param person */Public void Update (person) {sqlitedatabase DB = dbopenhelper. getwritabledatabase (); db.exe csql ("Update person set name = ?, Phone =? Where id =? ", New object [] {person. getname (), person. getphone (), person. GETID ()});}/*** Obtain Record * @ Param ID Record ID * @ return */public person find (integer ID) {sqlitedatabase DB = dbopenhelper. getreadabledatabase (); cursor = dB. rawquery ("select * From person where id =? ", New string [] {ID. tostring ()}); If (cursor. movetofirst () {string phone = cursor. getstring (cursor. getcolumnindex ("phone"); string name = cursor. getstring (cursor. getcolumnindex ("name"); cursor. close (); return new person (ID, name, phone);} return NULL ;} /*** retrieve record by PAGE ** @ Param offset skips the previous number of records * @ Param maxresult the number of records retrieved per page * @ return */public list <person> getscrolldata (INT offset, int maxresult) {lis T <person> Persons = new arraylist <person> (); sqlitedatabase DB = dbopenhelper. getreadabledatabase (); cursor = dB. rawquery ("select * From person order by id asc limit ?,? ", New string [] {string. valueof (offset), String. valueof (maxresult)}); While (cursor. movetonext () {int id = cursor. getint (cursor. getcolumnindex ("ID"); string phone = cursor. getstring (cursor. getcolumnindex ("phone"); string name = cursor. getstring (cursor. getcolumnindex ("name"); persons. add (new person (ID, name, phone);} cursor. close (); return persons;}/*** obtain the total number of records * @ return */public long getcount () {sqlitedatabase DB = dbopenhelper. getreadabledatabase (); cursor = dB. rawquery ("select count (*) from person", null); cursor. movetofirst (); Long Count = cursor. getlong (0); cursor. close (); Return count ;}}