我无法使我的数据库有效地存储信息。我正在使用Android Studio，正在尝试动态创建一个sqlite数据库并将信息插入其中。
我无法将信息插入到表中（我返回-1），但是，我不确定问题出在插入语句还是表/数据库创建。
这是代码。任何帮助将不胜感激..我已经为此努力了一段时间。
public class DatabaseHelper extends SQLiteOpenHelper {
private static final String TAG = "DatabaseHelper";
SQLiteDatabase database;
private static final String Database_Name = "CISP_340.db";
private static final String Table_Name = "ANIMALS";
private static final String col1 = "_ID";
private static final String col2 = "ANIMAL_TYPE_CD";
private static final String col3 = "COUNT_NO";
private static final String col4 = "SEENON_DTM";
private static final String col5 = "COMMENTS_TXT";
public DatabaseHelper(Context context){
super(context, Table_Name, null, 1);
database = getWritableDatabase();
}
@Override
public void onCreate(SQLiteDatabase db) {
String createTable = "CREATE TABLE " + Table_Name + " (ID INTEGER PRIMARY KEY AUTOINCREMENT, "+
col2 + " INTEGER DEFAULT 0, " +
col3 +" INTEGER, " +
col4 + " TEXT, " +
col5 + " TEXT)";
db.execSQL(createTable);
}
@Override
public void onUpgrade(SQLiteDatabase db, int i, int i1) {
db.execSQL("DROP IF TABLE EXISTS " + Table_Name);
onCreate(db);
}
public boolean addData(Animal animal){
ContentValues contentValues = new ContentValues();
contentValues.put(col5, animal.getComments());
Log.d(TAG, "addData: Adding " + animal.toString() + " to " + Table_Name);
long result = database.insert(Table_Name, null, contentValues);
if (result == -1) {
return false;
}else{
return true;
}
}
public Cursor getData(){
SQLiteDatabase db = this.getWritableDatabase();
String query = "SELECT * FROM " + Table_Name;
Cursor data = db.rawQuery(query, null);
return data;
}
}
这是我的动物课：
public class Animal {
Animal(){
//Blank
}
Animal(int animalType, int count, String seenOn, String comments){
this.animalType = animalType;
this.count = count;
this.seenOn = seenOn;
this.comments = comments;
}
private int animalType;
private int count;
private String seenOn;
private String comments;
public int getAnimalType() {
return animalType;
}
public void setAnimalType(int type){
this.animalType = type;
}
public int getCount() {
return count;
}
public void setCount(int count){
this.count = count;
}
public String getSeenOn() {
return seenOn;
}
public void setSeenOn(String seenOn){
this.seenOn = seenOn;
}
public String getComments() {
return comments;
}
public void setComments(String comments){
this.comments = comments;
}
@Override
public String toString(){
return "Animal type: " + animalType + ", Animal count: " + count + ", Animal was seen on: " + seenOn + ", Comments about encounter: " + comments;
}
}
这是我的MainActivity：
public class MainActivity extends AppCompatActivity {
private static final String TAG = "MainActivity";
DatabaseHelper dataBaseHelper;
private Button btnAdd, btnView;
private EditText editText;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
editText = (EditText) findViewById(R.id.editText);
btnAdd = (Button) findViewById(R.id.btnAdd);
btnView = (Button) findViewById(R.id.btnView);
dataBaseHelper = new DatabaseHelper(this);
Animal myAnimal = new Animal(1, 0, "Yes", "Raining");
Animal myAnimal2 = new Animal(1, 0, "No", "");
addAnimal(myAnimal);
addAnimal(myAnimal2);
btnAdd.setOnClickListener(new View.OnClickListener(){
@Override
public void onClick(View v){
Animal animal = new Animal();
animal.setComments(editText.getText().toString());
if (editText.length() != 0){
addAnimal(animal);
editText.setText("");
}else{
returnMessage("You must put something into this field");
}
}
});
btnView.setOnClickListener(new View.OnClickListener(){
@Override
public void onClick(View v){
Intent intent = new Intent(MainActivity.this, ListDataActivity.class);
startActivity(intent);
}
});
}
public void addAnimal( Animal animal ){
boolean insertData = dataBaseHelper.addData(animal);
if (insertData){
returnMessage("Success");
}else{
returnMessage("Fail");
}
}
private void returnMessage(String message){
Toast.makeText(this, message, Toast.LENGTH_SHORT).show();
}
}
尝试插入构造函数时在LogCat中输出：
12-02 17:20:23.624 4100-4100/edu.davenport.cisp340.animaltracker E/SQLiteDatabase: Error inserting COUNT_NO=0 ANIMAL_TYPE_CD=1 SEENON_DTM=Yes COMMENTS_TXT=Raining
android.database.sqlite.SQLiteException: table ANIMALS has no column named SEENON_DTM (code 1): , while compiling: INSERT INTO ANIMALS(COUNT_NO,ANIMAL_TYPE_CD,SEENON_DTM,COMMENTS_TXT) VALUES (?,?,?,?)
at android.database.sqlite.SQLiteConnection.nativePrepareStatement(Native Method)
at android.database.sqlite.SQLiteConnection.acquirePreparedStatement(SQLiteConnection.java:889)
at android.database.sqlite.SQLiteConnection.prepare(SQLiteConnection.java:500)
at android.database.sqlite.SQLiteSession.prepare(SQLiteSession.java:588)
at android.database.sqlite.SQLiteProgram.<init>(SQLiteProgram.java:58)
at android.database.sqlite.SQLiteStatement.<init>(SQLiteStatement.java:31)
at android.database.sqlite.SQLiteDatabase.insertWithOnConflict(SQLiteDatabase.java:1472)
at android.database.sqlite.SQLiteDatabase.insert(SQLiteDatabase.java:1343)
at edu.davenport.cisp340.animaltracker.DatabaseHelper.addData(DatabaseHelper.java:59)
at edu.davenport.cisp340.animaltracker.MainActivity.addAnimal(MainActivity.java:65)
at edu.davenport.cisp340.animaltracker.MainActivity.onCreate(MainActivity.java:32)
at android.app.Activity.performCreate(Activity.java:6980)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1213)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2770)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2892)
at android.app.ActivityThread.-wrap11(Unknown Source:0)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1593)
at android.os.Handler.dispatchMessage(Handler.java:105)
at android.os.Looper.loop(Looper.java:164)
at android.app.ActivityThread.main(ActivityThread.java:6540)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.Zygote$MethodAndArgsCaller.run(Zygote.java:240)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:767)
答案 0 :(得分：1)
现在，您已添加日志。问题是 SEENON_DTM 列不存在。
按照：-
table ANIMALS has no column named SEENON_DTM 自从运行App以来，您可能已经添加了该列。仅修改onCreate方法使用的SQL不足以更改数据库的结构。即onCreate仅在创建数据库时运行一次，然后将数据库保存到文件中，并因此保存在文件中。随后实例化DatabaseHelper，找到文件并且不调用onCreate。
如果丢失任何数据（可能不会存在有用的数据），解决方法不成问题，请执行以下一项操作；
super(context, Table_Name, null, 1);更改为super(context, Table_Name, null, 2);（1到2）
，然后重新运行该应用程序。
我相信您的代码不是问题（代码中唯一的问题是DROP IF TABLE EXISTS，应该是DROP TABLE IF EXISTS）。
您的代码可以按预期运行（请参见下文），因此问题出在您是如何检查数据还是由Animal类引起的。
下面的代码使用您的DatabaseHelper代码并从Activity中调用它（动物类可能与您的不同）。
我建议尝试下面的代码，针对您的DatabaseHelper类进行适当调整（即，将AnimalDBhelper更改为DatabaseHelper），然后检查日志。输出应如下所示（如果您添加了行并且未删除数据库，则可能会有更多行）。
使用代码的副本（将类重命名为AnimalDBhelper以适合我的测试环境），然后在活动中使用以下代码（调用代码）：-
public class MainActivity extends AppCompatActivity {
AnimalDBhelper mADBHlpr;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main_activity);
// Create two animals
mADBHlpr = new AnimalDBhelper(this);
Animal myanimal1 = new Animal(1,0,"Yes","Raining");
Animal myanimal2 = new Animal(1,0,"No","");
mADBHlpr.addData(myanimal1); // Add the first animal
Cursor csr = mADBHlpr.getData(); get the data
DatabaseUtils.dumpCursor(csr); dump the data (write it to the log)
mADBHlpr.addData(myanimal2); // Add the 2nd
csr = mADBHlpr.getData();
DatabaseUtils.dumpCursor(csr);
csr.close(); // Done with the cursor so close
}
}
12-02 19:37:54.040 1172-1172/? D/DatabaseHelper: addData: Adding ?.Animal@534af570 to ANIMALS
12-02 19:37:54.044 1172-1172/? I/System.out: >>>>> Dumping cursor android.database.sqlite.SQLiteCursor@534a5df8
12-02 19:37:54.044 1172-1172/? I/System.out: 0 {
12-02 19:37:54.044 1172-1172/? I/System.out: ID=1
12-02 19:37:54.044 1172-1172/? I/System.out: ANIMAL_TYPE_CD=0
12-02 19:37:54.044 1172-1172/? I/System.out: COUNT_NO=null
12-02 19:37:54.044 1172-1172/? I/System.out: SEENON_DTM=null
12-02 19:37:54.044 1172-1172/? I/System.out: COMMENTS_TXT=Raining
12-02 19:37:54.044 1172-1172/? I/System.out: }
12-02 19:37:54.044 1172-1172/? I/System.out: <<<<<
12-02 19:37:54.044 1172-1172/? D/DatabaseHelper: addData: Adding ?.Animal@534af5c4 to ANIMALS
12-02 19:37:54.048 1172-1172/? I/System.out: >>>>> Dumping cursor android.database.sqlite.SQLiteCursor@534ab7d4
12-02 19:37:54.048 1172-1172/? I/System.out: 0 {
12-02 19:37:54.048 1172-1172/? I/System.out: ID=1
12-02 19:37:54.048 1172-1172/? I/System.out: ANIMAL_TYPE_CD=0
12-02 19:37:54.048 1172-1172/? I/System.out: COUNT_NO=null
12-02 19:37:54.048 1172-1172/? I/System.out: SEENON_DTM=null
12-02 19:37:54.048 1172-1172/? I/System.out: COMMENTS_TXT=Raining
12-02 19:37:54.048 1172-1172/? I/System.out: }
12-02 19:37:54.048 1172-1172/? I/System.out: 1 {
12-02 19:37:54.048 1172-1172/? I/System.out: ID=2
12-02 19:37:54.048 1172-1172/? I/System.out: ANIMAL_TYPE_CD=0
12-02 19:37:54.048 1172-1172/? I/System.out: COUNT_NO=null
12-02 19:37:54.048 1172-1172/? I/System.out: SEENON_DTM=null
12-02 19:37:54.048 1172-1172/? I/System.out: COMMENTS_TXT=
12-02 19:37:54.048 1172-1172/? I/System.out: }
12-02 19:37:54.048 1172-1172/? I/System.out: <<<<<
答案 1 :(得分：0)
您尚未真正描述出了什么问题（正在查询游标而不找到所需的数据吗？），但是您需要将游标关闭在某个地方（see this answer），并且不需要由于您已经拥有getComment()中的数据库。这是应该在您的示例类中使用的版本。
public String getComment(){
String query = "SELECT * FROM " + Table_Name;
String comments = "";
Cursor data = database.rawQuery(query, null);
if( data.moveToFirst() ) { // iterate all the rows of the table
do {
String val = data.getString(4); // pull out column 5
// String val = data.getString(data.getColumnIndex(col5)); // or this way if you prefer
comments += val; // do something with the data - e.g. rebuild Animal object
} while (data.moveToNext());
}
data.close();
return comments;
}