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  • Android笔记(四十二) Android中的数据存储——SQLite(四)update

     

      update方法的四个参数:

    update()方法参数 对应的sql部分 描述
    table update table_name 更新的表名
    values set column=xxx ContentValues
    whereClause where column 修改条件
    whereArgs where column = xx 修改条件的参数

             看代码:

    MainActivity.java

    package cn.lixyz.sqlite;
    
    import android.app.Activity;
    import android.content.ContentValues;
    import android.content.Context;
    import android.database.Cursor;
    import android.database.sqlite.SQLiteDatabase;
    import android.database.sqlite.SQLiteDatabase.CursorFactory;
    import android.database.sqlite.SQLiteOpenHelper;
    import android.os.Bundle;
    import android.util.Log;
    import android.view.View;
    import android.widget.Button;
    import android.widget.EditText;
    import android.widget.Toast;
    
    public class MainActivity extends Activity {
    
        private EditText name, age, paramter, originalAge, newAge;
        private Button insertButton, selectButton, paramterSelect, updateButton;
    
        private SQLiteDatabase database;
        private MySQLiteOpenHelper msop;
    
        public String inputSex;
    
        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_main);
    
            findView();
    
            msop = new MySQLiteOpenHelper(this, "user.db", null, 1);
            database = msop.getReadableDatabase();
    
        }
    
        private void findView() {
            name = (EditText) findViewById(R.id.name);
            age = (EditText) findViewById(R.id.age);
            insertButton = (Button) findViewById(R.id.insertButton);
            selectButton = (Button) findViewById(R.id.selectButton);
            paramter = (EditText) findViewById(R.id.paramter);
            paramterSelect = (Button) findViewById(R.id.paramterSelect);
            originalAge = (EditText) findViewById(R.id.originalAge);
            newAge = (EditText) findViewById(R.id.newAge);
            updateButton = (Button) findViewById(R.id.updateButton);
        }
    
        public void clickButton(View view) {
            switch (view.getId()) {
            case R.id.selectButton:
                selectData();
                break;
    
            case R.id.insertButton:
                insertData();
                break;
            case R.id.paramterSelect:
                paramterSelect();
                break;
            case R.id.updateButton:
                updateData();
                break;
            }
        }
    
        private void updateData() {
            String oldAge = originalAge.getText().toString();
            String updateAge = newAge.getText().toString();
            ContentValues cv = new ContentValues();
            cv.put("age", updateAge);
            String whereColumn = "age=?";// 修改条件
            String[] whereArgs = { oldAge };
            int i = database.update("user", cv, whereColumn, whereArgs);
            if (1 > 0) {
                Toast.makeText(MainActivity.this, "更新成功", Toast.LENGTH_SHORT).show();
            } else {
                Toast.makeText(MainActivity.this, "更新不成功", Toast.LENGTH_SHORT).show();
            }
        }
    
        private void paramterSelect() {
            String inputAge = paramter.getText().toString();
            Cursor c = database.rawQuery("select * from user where age>?", new String[] { inputAge });
            if (c.moveToFirst()) {
                do {
                    int id = c.getInt(c.getColumnIndex("id"));
                    String name = c.getString(c.getColumnIndex("name"));
                    String age = c.getString(c.getColumnIndex("age"));
                    Log.d("TTTT", "id=" + id + ",name=" + name + ",age=" + age);
                } while (c.moveToNext());
            }
            c.close();
    
        }
    
        private void insertData() {
            String inputAge = age.getText().toString();
            String inputName = name.getText().toString();
            ContentValues cv = new ContentValues();
            cv.put("name", inputName);
            cv.put("age", inputAge);
            database.insert("user", null, cv);
            Toast.makeText(MainActivity.this, "插入成功", Toast.LENGTH_SHORT).show();
            age.setText("");
            name.setText("");
    
        }
    
        private void selectData() {
            Cursor c = database.query("user", null, null, null, null, null, null);
            if (c.moveToFirst()) {
                do {
                    int id = c.getInt(c.getColumnIndex("id"));
                    String name = c.getString(c.getColumnIndex("name"));
                    String age = c.getString(c.getColumnIndex("age"));
                    Log.d("TTTT", "id=" + id + ",姓名=" + name + ",年龄=" + age);
                } while (c.moveToNext());
            }
            c.close();
    
        }
    
        class MySQLiteOpenHelper extends SQLiteOpenHelper {
    
            private static final String CREATE_USER = "create table user(id integer primary key autoincrement,name text,age text)";
    
            private Context mContext;
    
            public MySQLiteOpenHelper(Context context, String name, CursorFactory factory, int version) {
                super(context, name, factory, version);
                mContext = context;
            }
    
            @Override
            public void onCreate(SQLiteDatabase db) {
                db.execSQL(CREATE_USER);
            }
    
            @Override
            public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
                // TODO Auto-generated method stub
    
            }
    
        }
    }

    activity_main.xml

    <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:tools="http://schemas.android.com/tools"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="vertical"
        tools:context=".MainActivity" >
    
        <EditText
            android:id="@+id/name"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:hint="输入姓名" />
    
        <EditText
            android:id="@+id/age"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:hint="输入年龄" />
    
        <Button
            android:id="@+id/insertButton"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:onClick="clickButton"
            android:text="点击插入" />
    
        <Button
            android:id="@+id/selectButton"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:onClick="clickButton"
            android:text="点击查询" />
    
        <TextView
            android:id="@+id/text"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:text="条件搜索" />
    
        <EditText
            android:id="@+id/paramter"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:hint="您要搜多少岁以上的?" />
    
        <Button
            android:id="@+id/paramterSelect"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:onClick="clickButton"
            android:text="点击搜索" />
    
        <TextView
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:text="update" />
    
        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:orientation="horizontal" >
    
            <EditText
                android:id="@+id/originalAge"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:hint="要修改的年龄" />
    
            <TextView
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text="修改为" />
    
            <EditText
                android:id="@+id/newAge"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:hint="新年龄" />
        </LinearLayout>
    
        <Button
            android:id="@+id/updateButton"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:onClick="clickButton"
            android:text="UPDATE" />
    
    </LinearLayout>

      运行结果:

      通过结果可以看到,将之前数据库内的年龄为12的修改为20

     

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  • 原文地址:https://www.cnblogs.com/xs104/p/4916119.html
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