Question

我在student.db课程中创建了一个名为Student_profile的数据库和两个表Teacher_profile和DatabaseHelper。当我将数据插入第一个表时，它会被插入但不会在我尝试使用第二个表时插入。我确定在从我用来插入数据的活动的EditText字段中识别值时，我没有犯任何错误。一个特别需要注意的事情是，如果我插入第二个表Teacher_profile的条目，调用它插入的第一个表insertData1的{{1}}函数（两个表具有相同类型的列和相同的列数）但是当我调用它的合法Student_profile函数时，我的问题确实存在。

我使用了三个java文件：

MainActivity - ＆gt;插入student_profile表
老师 - ＆gt;插入teacher_profile表
DatabaseHelper - ＆gt;用于插入数据库的代码的java代码。

insertData2

package com.example.point.sqlite;

import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;

public class DatabaseHelperClass extends SQLiteOpenHelper {

public static final String Database_name="student.db";

public static final String Table_name="Student_profile";
public static final String col1="id";
public static final String col2="name";
public static final String col3="surname";
public static final String col4="marks";

public static final String Table_name2="Teacher_profile";
public static final String cl1="id";
public static final String cl2="name";
public static final String cl3="surname";
public static final String cl4="age";




public DatabaseHelperClass(Context context) {
    super(context, Database_name, null, 1);//whenever the constructor will be called the database will be created
}

@Override
public void onCreate(SQLiteDatabase db) {
    db.execSQL("create table "+ Table_name+"(id integer primary key autoincrement,name text,surname text,marks integer)");
    db.execSQL("create table "+ Table_name2+"(id integer primary key autoincrement,name text,surname text,age integer)");


}

@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {

    db.execSQL("drop table"+Table_name);
    db.execSQL("drop table"+Table_name2);

    onCreate(db);
}
//for inserting the student records
public boolean insertData(String name,String surname,String marks){

    SQLiteDatabase db=this.getWritableDatabase();

    ContentValues cont=new ContentValues();
    cont.put(col2,name);
    cont.put(col3, surname);
    cont.put(col4,marks);
    long result=db.insert(Table_name,null,cont);
    if(result==-1) {
        return false;
    }
    else
        return true;

}
// for showing student records
public Cursor showDatabase()
{
    SQLiteDatabase db=this.getWritableDatabase();
    Cursor res=db.rawQuery("select * from "+ Table_name,null);
    return  res;
}
//for inserting teacher record
public boolean insertData2(String name,String surname,String age){

    SQLiteDatabase db=this.getWritableDatabase();

    ContentValues cont=new ContentValues();
    cont.put(col2,name);
    cont.put(col3, surname);
    cont.put(col4,age);
    long result=db.insert(Table_name2,null,cont);
    if(result==-1) {
        return false;
    }
    else
        return true;

}
//for showing teacher record
public Cursor showDatabase2()
{
    SQLiteDatabase db=this.getWritableDatabase();
    Cursor res=db.rawQuery("select * from "+ Table_name2,null);
    return  res;
}
public boolean updateDatabaseTable(String id,String name,String surname,String marks){
    SQLiteDatabase db=this.getWritableDatabase();
    ContentValues cont=new ContentValues();
    cont.put(col1,id);
    cont.put(col2,name);
    cont.put(col3, surname);
    cont.put(col4,marks);
    db.update(Table_name,cont,"id = ?",new String[] {id});//id is the parameter
    return true;

}
public int deleteData(String id)
{
    SQLiteDatabase db=this.getWritableDatabase();

    return db.delete(Table_name,"id = ?",new String[] {id}); }}

package com.example.point.sqlite;

import android.app.Activity;

import android.app.AlertDialog;
import android.content.Intent;
import android.database.Cursor;
import android.os.Bundle;
import.android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;


public class MainActivity extends Activity {

DatabaseHelperClass myDb;
EditText ed1,ed2,ed3,id;
Button b;//button to insert into student table
Button teacher,showData,updateData,delData;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    myDb=new DatabaseHelperClass(this);
    ed1=(EditText)findViewById(R.id.editText);//name
    ed2=(EditText)findViewById(R.id.editText2);//surname
    ed3=(EditText)findViewById(R.id.editText4);//marks
    b=(Button)findViewById(R.id.button);//insert button for student
    teacher=(Button)findViewById(R.id.button5);//button to go to teacher.java
    showData=(Button)findViewById(R.id.button2);
    updateData=(Button)findViewById(R.id.button3);
    delData=(Button)findViewById(R.id.button4);
    id=(EditText)findViewById(R.id.editText3);//id
//this works well and data get inserted 
    b.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            boolean isInserted=myDb.insertData(ed1.getText().toString(), ed2.getText().toString(), ed3.getText().toString());
            if(isInserted==true)
            {
                Toast.makeText(getApplicationContext(),"data inserted",Toast.LENGTH_LONG).show();
            }
            else
                Toast.makeText(getApplicationContext(),"data not inserted",Toast.LENGTH_LONG).show();
            setEmpty();


        }
    });



    teacher.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            Intent i=new Intent(getApplicationContext(),Teacher.class);
            startActivity(i);
        }
    });
    updateData.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {

            boolean res= myDb.updateDatabaseTable(id.getText().toString(),ed1.getText().toString(),ed2.getText().toString(),ed3.getText().toString());
            if(res==true)
            {
                Toast.makeText(getApplicationContext(),"data updated",Toast.LENGTH_LONG).show();

            }
            else
                Toast.makeText(getApplicationContext(),"data not updated",Toast.LENGTH_LONG).show();

          setEmpty();
        }
    });





    showData.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            Cursor res = myDb.showDatabase();
            if (res.getCount() == 0)
            {
                showMessage("Error!", "no data found");
                return;
            }
            StringBuffer bf = new StringBuffer();
            while (res.moveToNext())
            {

                bf.append("ID: " + res.getString(0)+"\n");//0 for first column that is col1 id
                bf.append("NAME: " + res.getString(1)+"\n");
                bf.append("SURNAME: " + res.getString(2)+"\n");
                bf.append("MARKS: " + res.getString(3)+"\n\n");
            }
            showMessage("Data",bf.toString());

            setEmpty();
        }

    });



    delData.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {

            int deletedRows=myDb.deleteData(id.getText().toString());
            if(deletedRows>0)
                Toast.makeText(getApplicationContext(),"data deleted",Toast.LENGTH_LONG).show();
            else
                Toast.makeText(getApplicationContext(),"data not deleted",Toast.LENGTH_LONG).show();

            setEmpty();


        }

    });


}

public void setEmpty()
{
    ed1.setText("");
    ed2.setText("");
    ed3.setText("");
    id.setText("");
}
public void showMessage(String title,String message)
{
    AlertDialog.Builder build=new AlertDialog.Builder(this);

    build.setCancelable(true);
    build.setTitle(title);
    build.setMessage(message);
    build.show();
}


@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.menu_main, menu);
    return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    // Handle action bar item clicks here. The action bar will
    // automatically handle clicks on the Home/Up button, so long
    // as you specify a parent activity in AndroidManifest.xml.
    int id = item.getItemId();

    //noinspection SimplifiableIfStatement
    if (id == R.id.action_settings) {
        return true;
    }

    return super.onOptionsItemSelected(item);
}
}`

Answer 1

检查您的第二个表格插入方法insertData2，并使用列名cl2代替col2，并使用相同的其他

Answer 2

你必须使用..

public boolean insertData2(String name,String surname,String age){

    SQLiteDatabase db=this.getWritableDatabase();

    ContentValues cont=new ContentValues();
    cont.put(cl2,name);
    cont.put(cl3, surname);
    cont.put(cl4,age);
    long result=db.insert(Table_name2,null,cont);
    if(result==-1) {
        return false;
    }
    else
        return true;

}

而不是

public boolean insertData2(String name,String surname,String age){

    SQLiteDatabase db=this.getWritableDatabase();

    ContentValues cont=new ContentValues();
    cont.put(col2,name);
    cont.put(col3, surname);
    cont.put(col4,age);
    long result=db.insert(Table_name2,null,cont);
    if(result==-1) {
        return false;
    }
    else
        return true;

}

无法在android

2 个答案: