android两种方法操作Sqlite数据库

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="fill_parent"    android:layout_height="fill_parent"    android:orientation="vertical" >    <LinearLayout        android:layout_width="match_parent"        android:layout_height="wrap_content" >        <Button            android:id="@+id/insertButton"            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:text="插入" />        <EditText            android:id="@+id/insertEditText"            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:layout_weight="1"            android:ems="10" >            <requestFocus />        </EditText>    </LinearLayout>     <LinearLayout        android:layout_width="match_parent"        android:layout_height="wrap_content" >        <Button            android:id="@+id/deleteButton"            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:text="删除" />        <EditText            android:id="@+id/deleteEditText"            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:layout_weight="1"            android:ems="10" />    </LinearLayout>                <LinearLayout        android:layout_width="match_parent"        android:layout_height="wrap_content" >        <Button            android:id="@+id/updateButton"            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:text="修改" />        <EditText            android:id="@+id/oldEditText"            android:layout_width="119dp"            android:layout_height="wrap_content"            android:ems="10" />        <TextView            android:id="@+id/textView3"            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:text="改为" />        <EditText            android:id="@+id/newEditText"            android:layout_width="92dp"            android:layout_height="wrap_content"            android:ems="10" />    </LinearLayout>       <Button        android:id="@+id/selectButton"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:text="查询" />    <TextView        android:id="@+id/resultTextView"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:text="结果" /></LinearLayout>

</pre><pre name="code" class="java"><pre name="code" class="java">package com.example.sqlite_2;import android.app.Activity;import android.content.ContentValues;import android.database.Cursor;import android.database.sqlite.SQLiteDatabase;import android.os.Bundle;import android.util.Log;import android.view.Menu;import android.view.MenuItem;import android.view.View;import android.view.View.OnClickListener;import android.widget.Button;import android.widget.EditText;import android.widget.TextView;public class MainActivity extends Activity {private Button insertButton, updateButton, deleteButton, selectButton;private EditText insertEditText, oldEditText, newEditText, deleteEditText;private TextView resultTextView;private StringBuilder sb = new StringBuilder();@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);insertButton = (Button) findViewById(R.id.insertButton);deleteButton = (Button) findViewById(R.id.deleteButton);updateButton = (Button) findViewById(R.id.updateButton);selectButton = (Button) findViewById(R.id.selectButton);insertEditText = (EditText) findViewById(R.id.insertEditText);oldEditText = (EditText) findViewById(R.id.oldEditText);newEditText = (EditText) findViewById(R.id.newEditText);deleteEditText = (EditText) findViewById(R.id.deleteEditText);resultTextView = (TextView) findViewById(R.id.resultTextView);// //增insertButton.setOnClickListener(new OnClickListener() {@Overridepublic void onClick(View v) {// TODO 自动生成的方法存根insert();}});// 删deleteButton.setOnClickListener(new OnClickListener() {@Overridepublic void onClick(View v) {// TODO 自动生成的方法存根Log.i("删除开始", "删除开始");delete();Log.i("删除结束", "删除结束");}});// //改updateButton.setOnClickListener(new OnClickListener() {@Overridepublic void onClick(View v) {// TODO 自动生成的方法存根// db.update(table, values, whereClause, whereArgs)update();}});// //查selectButton.setOnClickListener(new OnClickListener() {@Overridepublic void onClick(View v) {// TODO 自动生成的方法存根if (getCount()>0) {select();} else {resultTextView.setText("结果为空");}}});}// /onCreateprivate void insert() {CityDBHelper dbHelper = new CityDBHelper(MainActivity.this,"city_db_3", null, 1);SQLiteDatabase db = dbHelper.getWritableDatabase();// ContentValues cv = new ContentValues();// cv.put("city", insertEditText.getText().toString());// db.insert("city_table", null, cv);// db.close();//// resultTextView.setText("");db.execSQL("insert into city_table(city) values(?)",new Object[] { insertEditText.getText().toString() });}private void delete() {CityDBHelper dbHelper = new CityDBHelper(MainActivity.this,"city_db_3", null, 1);SQLiteDatabase db = dbHelper.getReadableDatabase();// String whereClauses = "city=?";// Log.i(" deleteEditText.getText().toString()",// deleteEditText.getText()// .toString());//// String[] whereArgs = { deleteEditText.getText().toString() };// db.delete("city_table", whereClauses, whereArgs);db.execSQL("delete  from   city_table where  city= ? ",new Object[] { deleteEditText.getText().toString() });}private void update() {CityDBHelper dbHelper = new CityDBHelper(MainActivity.this,"city_db_3", null, 1);SQLiteDatabase db = dbHelper.getWritableDatabase();//// ContentValues cv = new ContentValues();// cv.put("city", newEditText.getText().toString());// String whereClauses = "city=?";// String[] whereArgs = { oldEditText.getText().toString() };// db.update("city_table", cv, whereClauses, whereArgs);db.execSQL("update  city_table  set city=? where city  =?",new Object[] { newEditText.getText().toString(),oldEditText.getText().toString() });}private void select() {CityDBHelper dbHelper = new CityDBHelper(MainActivity.this,"city_db_3", null, 1);SQLiteDatabase db = dbHelper.getWritableDatabase();// Cursor cursor = db.query("city_table", new String[] { "city" }, null,// null, null, null, null, null);// sb.delete(0, sb.length());// while (cursor.moveToNext()) {// sb.append("城市:" + cursor.getString(cursor.getColumnIndex("city"))// + "\n");// }// resultTextView.setText(sb.toString());// db.close();sb.delete(0, sb.length());Cursor cursor = db.rawQuery("select *  from   city_table ", null);while (cursor.moveToNext()) {sb.append("城市:" + cursor.getString(0)+ "\n");}resultTextView.setText(sb.toString());}// private boolean boolean_select() {//// CityDBHelper dbHelper = new CityDBHelper(MainActivity.this,// "city_db_3", null, 1);//// SQLiteDatabase db = dbHelper.getWritableDatabase();// Cursor cursor = db.query("city_table", new String[] { "city" }, null,// null, null, null, null, null);// if (cursor.getCount() > 0) {// db.close();// return true;//// }//// return false;//// }private int getCount() {int count = 0;CityDBHelper dbHelper = new CityDBHelper(MainActivity.this,"city_db_3", null, 1);SQLiteDatabase db = dbHelper.getWritableDatabase();Cursor cursor = db.rawQuery("select  count(*) from   city_table  ",null);while (cursor.moveToNext()) {count = cursor.getInt(0);Log.i("count", String.valueOf(count));}return count;}}

<pre name="code" class="java">package com.example.sqlite_2;import android.content.Context;import android.database.sqlite.SQLiteDatabase;import android.database.sqlite.SQLiteDatabase.CursorFactory;import android.database.sqlite.SQLiteOpenHelper;public class CityDBHelper  extends SQLiteOpenHelper  {private   final  static  int   VERSION=1;public CityDBHelper(Context context, String name, CursorFactory factory,int version) {super(context, name, factory, version);// TODO 自动生成的构造函数存根}@Overridepublic void onCreate(SQLiteDatabase db) {// TODO 自动生成的方法存根db.execSQL("create  table   city_table (city  varchar(50) )");}@Overridepublic void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {// TODO 自动生成的方法存根db.execSQL("alter  table   city_table   add   extends_column  varchar(10)");}}

注释掉的单独是一个方法，可用于增删改查

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