Android SQLite在启动时只读取一个表,而不修改第二个表
我正在尝试编写两个表的代码 一个用于保存某些鞋的信息,另一个用于保存品牌信息 虽然一只鞋很好用,但另一只却不行Android SQLite在启动时只读取一个表,而不修改第二个表,android,android-sqlite,multiple-tables,sqliteopenhelper,Android,Android Sqlite,Multiple Tables,Sqliteopenhelper,我正在尝试编写两个表的代码 一个用于保存某些鞋的信息,另一个用于保存品牌信息 虽然一只鞋很好用,但另一只却不行 public class AdminSQLiteOpenHelper extends SQLiteOpenHelper { public AdminSQLiteOpenHelper(@Nullable Context context, @Nullable String name, @Nullable SQLiteDatabase.CursorFactory factory, i
public class AdminSQLiteOpenHelper extends SQLiteOpenHelper {
public AdminSQLiteOpenHelper(@Nullable Context context, @Nullable String name, @Nullable SQLiteDatabase.CursorFactory factory, int version) {
super(context, name, factory, version);
}
@Override
public void onCreate(SQLiteDatabase db) {
String sql1 = "create table zaps(matricula text primary key,color text,talla text)";
String sql2 = "create table alumnos(matricula text primary key,nombre text,tel text)";
Log.d("Data", "onCreate: " + sql1);
Log.d("Data", "onCreate: " + sql2);
db.execSQL(sql1);
db.execSQL(sql2);
}
@Override
public void onUpgrade(SQLiteDatabase sqLiteDatabase, int i, int i1) {
}
}
这是我试图修改表格的品牌活动
public class ProvActivity extends AppCompatActivity {
EditText etMatricula, etNombre, etTel;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_prov);
etMatricula = (EditText) findViewById(R.id.etMatricula);
etNombre = (EditText) findViewById(R.id.etNombre);
etTel = (EditText) findViewById(R.id.etTel);
}
public void guardar(View v) {
try {
AdminSQLiteOpenHelper admin = new AdminSQLiteOpenHelper(this,
"administracion1", null, 1);
SQLiteDatabase bd1 = admin.getWritableDatabase();
ContentValues reg = new ContentValues();
reg.put("matricula", etMatricula.getText().toString());
reg.put("nombre", etNombre.getText().toString());
reg.put("tel", etTel.getText().toString());
bd1.insert("alumnos", null, reg);
bd1.close();
etMatricula.setText("");
etNombre.setText("");
etTel.setText("");
etMatricula.requestFocus();
Toast.makeText(this, "Se ha guardado el registro con éxito.",
Toast.LENGTH_SHORT).show();
} catch (Exception e) {
Toast.makeText(getApplicationContext(), e.getMessage(), Toast.LENGTH_SHORT);
}
}
public void consultar_matricula(View v) {
try {
AdminSQLiteOpenHelper admin = new AdminSQLiteOpenHelper(this,
"administracion1", null, 1);
SQLiteDatabase bd1 = admin.getWritableDatabase();
String cod = etMatricula.getText().toString();
Cursor fila = bd1.rawQuery(
"select nombre,tel from alumnos where matricula=" + cod, null);
if (fila.moveToFirst()) {
etNombre.setText(fila.getString(0));
etTel.setText(fila.getString(1));
} else
Toast.makeText(this, "No existe un registro con dicha matrícula.",
Toast.LENGTH_SHORT).show();
bd1.close();
} catch (Exception e) {
Toast.makeText(getApplicationContext(), e.getMessage(), Toast.LENGTH_SHORT);
}
}
}
您所显示的代码可以将数据插入数据库 因此,您可能存在以下常见问题之一 自运行应用程序以来,您已将另一个表添加到AdminSQLiteOpenHelper类的onCreate方法中的代码中。
- 数据库助手(扩展SQLiteOpenHelper的类)的onCreate方法在数据库的生命周期内只运行一次李>
- 要更改模式(例如,添加表),您必须将更改应用到其他地方(例如,通过onUpgrade方法,同时增加数据库版本),或者,如开发应用程序时经常发生的情况,删除数据库。您可以通过以下方式轻松删除数据库:-
- 卸载应用程序,或
- 正在删除应用程序的数据
public class AdminSQLiteOpenHelper extends SQLiteOpenHelper {
public AdminSQLiteOpenHelper(@Nullable Context context) {
super(context, "administracion1", null, 1);
}
/*
See above for easier to use constructor (just pass the Context)
*/
public AdminSQLiteOpenHelper(@Nullable Context context, @Nullable String name, @Nullable SQLiteDatabase.CursorFactory factory, int version) {
super(context, name, factory, version);
}
@Override
public void onCreate(SQLiteDatabase db) {
String sql1 = "create table zaps(matricula text primary key,color text,talla text)";
String sql2 = "create table alumnos(matricula text primary key,nombre text,tel text)";
Log.d("Data", "onCreate: " + sql1);
Log.d("Data", "onCreate: " + sql2);
db.execSQL(sql1);
db.execSQL(sql2);
}
@Override
public void onUpgrade(SQLiteDatabase sqLiteDatabase, int i, int i1) {
}
/*
Added to simplify testing
*/
public long insertAlumnos(String matricula, String nombre, String tel) {
ContentValues cv = new ContentValues();
cv.put("matricula",matricula);
cv.put("nombre",nombre);
cv.put("tel",tel);
SQLiteDatabase db = this.getWritableDatabase();
return db.insert("alumnos",null,cv);
}
public long insertZaps(String matricula, String color, String talla) {
ContentValues cv = new ContentValues();
cv.put("matricula",matricula);
cv.put("color",color);
cv.put("talla",talla);
SQLiteDatabase db = this.getWritableDatabase();
return db.insert("zaps",null,cv);
}
public void logAllZaps() {
logAllRows("zaps");
}
public void logAllAlumnos() {
logAllRows("alumnos");
}
private void logAllRows(String table) {
SQLiteDatabase db = this.getWritableDatabase();
Cursor csr = db.query(table,null,null,null,null,null,null);
DatabaseUtils.dumpCursor(csr);
csr.close();
}
}
- 这通常是由于试图通过GUI确定数据的存在,但没有刷新显示的数据
public class AdminSQLiteOpenHelper extends SQLiteOpenHelper {
public AdminSQLiteOpenHelper(@Nullable Context context) {
super(context, "administracion1", null, 1);
}
/*
See above for easier to use constructor (just pass the Context)
*/
public AdminSQLiteOpenHelper(@Nullable Context context, @Nullable String name, @Nullable SQLiteDatabase.CursorFactory factory, int version) {
super(context, name, factory, version);
}
@Override
public void onCreate(SQLiteDatabase db) {
String sql1 = "create table zaps(matricula text primary key,color text,talla text)";
String sql2 = "create table alumnos(matricula text primary key,nombre text,tel text)";
Log.d("Data", "onCreate: " + sql1);
Log.d("Data", "onCreate: " + sql2);
db.execSQL(sql1);
db.execSQL(sql2);
}
@Override
public void onUpgrade(SQLiteDatabase sqLiteDatabase, int i, int i1) {
}
/*
Added to simplify testing
*/
public long insertAlumnos(String matricula, String nombre, String tel) {
ContentValues cv = new ContentValues();
cv.put("matricula",matricula);
cv.put("nombre",nombre);
cv.put("tel",tel);
SQLiteDatabase db = this.getWritableDatabase();
return db.insert("alumnos",null,cv);
}
public long insertZaps(String matricula, String color, String talla) {
ContentValues cv = new ContentValues();
cv.put("matricula",matricula);
cv.put("color",color);
cv.put("talla",talla);
SQLiteDatabase db = this.getWritableDatabase();
return db.insert("zaps",null,cv);
}
public void logAllZaps() {
logAllRows("zaps");
}
public void logAllAlumnos() {
logAllRows("alumnos");
}
private void logAllRows(String table) {
SQLiteDatabase db = this.getWritableDatabase();
Cursor csr = db.query(table,null,null,null,null,null,null);
DatabaseUtils.dumpCursor(csr);
csr.close();
}
}
- 请注意,添加/更改是在最初检查代码之后进行的。这些变化只是让测试变得更容易
public class AdminSQLiteOpenHelper extends SQLiteOpenHelper {
public AdminSQLiteOpenHelper(@Nullable Context context) {
super(context, "administracion1", null, 1);
}
/*
See above for easier to use constructor (just pass the Context)
*/
public AdminSQLiteOpenHelper(@Nullable Context context, @Nullable String name, @Nullable SQLiteDatabase.CursorFactory factory, int version) {
super(context, name, factory, version);
}
@Override
public void onCreate(SQLiteDatabase db) {
String sql1 = "create table zaps(matricula text primary key,color text,talla text)";
String sql2 = "create table alumnos(matricula text primary key,nombre text,tel text)";
Log.d("Data", "onCreate: " + sql1);
Log.d("Data", "onCreate: " + sql2);
db.execSQL(sql1);
db.execSQL(sql2);
}
@Override
public void onUpgrade(SQLiteDatabase sqLiteDatabase, int i, int i1) {
}
/*
Added to simplify testing
*/
public long insertAlumnos(String matricula, String nombre, String tel) {
ContentValues cv = new ContentValues();
cv.put("matricula",matricula);
cv.put("nombre",nombre);
cv.put("tel",tel);
SQLiteDatabase db = this.getWritableDatabase();
return db.insert("alumnos",null,cv);
}
public long insertZaps(String matricula, String color, String talla) {
ContentValues cv = new ContentValues();
cv.put("matricula",matricula);
cv.put("color",color);
cv.put("talla",talla);
SQLiteDatabase db = this.getWritableDatabase();
return db.insert("zaps",null,cv);
}
public void logAllZaps() {
logAllRows("zaps");
}
public void logAllAlumnos() {
logAllRows("alumnos");
}
private void logAllRows(String table) {
SQLiteDatabase db = this.getWritableDatabase();
Cursor csr = db.query(table,null,null,null,null,null,null);
DatabaseUtils.dumpCursor(csr);
csr.close();
}
}
这只是一个简化的活动,它使用原始数据,而不是通过UI获取数据:-
public class MainActivity extends AppCompatActivity {
AdminSQLiteOpenHelper adminHelper;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
adminHelper = new AdminSQLiteOpenHelper(this);
adminHelper.insertZaps("test","red","blah");
adminHelper.insertAlumnos("test","199","0000000000");
adminHelper.logAllZaps();
adminHelper.logAllAlumnos();
//guardar();
//other();
}
/* Not USED although tested */
public void guardar() {
AdminSQLiteOpenHelper admin = new AdminSQLiteOpenHelper(this,
"administracion1", null, 1);
SQLiteDatabase bd1 = admin.getWritableDatabase();
ContentValues reg = new ContentValues();
reg.put("matricula", "test");
reg.put("nombre", "100");
reg.put("tel", "0000000000");
bd1.insert("alumnos", null, reg);
//bd1.close();
}
}
初次运行结果:-
2019-11-28 13:11:29.348 4788-4788/a.so59080227 D/Data: onCreate: create table zaps(matricula text primary key,color text,talla text)
2019-11-28 13:11:29.348 4788-4788/a.so59080227 D/Data: onCreate: create table alumnos(matricula text primary key,nombre text,tel text)
2019-11-28 13:11:29.368 4788-4788/a.so59080227 I/System.out: >>>>> Dumping cursor android.database.sqlite.SQLiteCursor@5df21a1
2019-11-28 13:11:29.371 4788-4788/a.so59080227 I/System.out: 0 {
2019-11-28 13:11:29.372 4788-4788/a.so59080227 I/System.out: matricula=test
2019-11-28 13:11:29.372 4788-4788/a.so59080227 I/System.out: color=red
2019-11-28 13:11:29.372 4788-4788/a.so59080227 I/System.out: talla=blah
2019-11-28 13:11:29.372 4788-4788/a.so59080227 I/System.out: }
2019-11-28 13:11:29.372 4788-4788/a.so59080227 I/System.out: <<<<<
2019-11-28 13:11:29.372 4788-4788/a.so59080227 I/System.out: >>>>> Dumping cursor android.database.sqlite.SQLiteCursor@fc68fc6
2019-11-28 13:11:29.373 4788-4788/a.so59080227 I/System.out: 0 {
2019-11-28 13:11:29.373 4788-4788/a.so59080227 I/System.out: matricula=test
2019-11-28 13:11:29.373 4788-4788/a.so59080227 I/System.out: nombre=199
2019-11-28 13:11:29.373 4788-4788/a.so59080227 I/System.out: tel=0000000000
2019-11-28 13:11:29.373 4788-4788/a.so59080227 I/System.out: }
2019-11-28 13:11:29.373 4788-4788/a.so59080227 I/System.out: <<<<<
2019-11-28 13:11:29.348 4788-4788/a.so59080227 D/Data:onCreate:create table zaps(矩阵文本主键、彩色文本、塔拉文本)
2019-11-28 13:11:29.348 4788-4788/a.so59080227 D/数据:onCreate:创建表alumnos(matricula text主键、nombre text、tel text)
2019-11-28 13:11:29.368 4788-4788/a.so59080227 I/System.out:>>>>>>>>转储游标android.database.sqlite。SQLiteCursor@5df21a1
2019-11-28 13:11:29.3714788-4788/a.so59080227 I/System.out:0{
2019-11-28 13:11:29.3724788-4788/a.so59080227 I/System.out:matricula=test
2019-11-28 13:11:29.3724788-4788/a.so59080227 I/System.out:color=red
2019-11-28 13:11:29.3724788-4788/a.so59080227 I/System.out:talla=blah
2019-11-28 13:11:29.3724788-4788/a.so59080227 I/System.out:}
2019-11-28 13:11:29.3724788-4788/a.so59080227 I/System.out:>转储游标android.database.sqlite。SQLiteCursor@fc68fc6
2019-11-28 13:11:29.373 4788-4788/a.so59080227 I/System.out:0{
2019-11-28 13:11:29.373 4788-4788/a.so59080227 I/System.out:matricula=test
2019-11-28 13:11:29.373 4788-4788/a.so59080227 I/System.out:nombre=199
2019-11-28 13:11:29.373 4788-4788/a.so59080227 I/System.out:tel=0000000000
2019-11-28 13:11:29.373 4788-4788/a.so59080227 I/System.out:}
2019-11-28 13:11:29.373 4788-4788/a.so59080227 I/System.out:您只需要使用SQLiteOpenHelper的onUpgrade方法,如下所示。可能您的第二个表现在没有创建因此,对于通用解决方案,您需要增加数据库版本(AdminSQLiteOpenHelper构造函数的第四个字段),并添加以下代码,而不是onUpgrade方法。
public class AdminSQLiteOpenHelper extends SQLiteOpenHelper {
public AdminSQLiteOpenHelper(@Nullable Context context, @Nullable String
name, @Nullable SQLiteDatabase.CursorFactory factory, int version) {
super(context, name, factory, version);
}
@Override
public void onCreate(SQLiteDatabase db) {
String sql1 = "create table if not exists zaps(matricula text primary
key,color text,talla text)";
String sql2 = "create table if not exists alumnos(matricula text primary
key,nombre text,tel text)";
Log.d("Data", "onCreate: " + sql1);
Log.d("Data", "onCreate: " + sql2);
db.execSQL(sql1);
db.execSQL(sql2);
}
@Override
public void onUpgrade(SQLiteDatabase sqLiteDatabase, int i, int i1) {
String sql1 = "create table if not exists zaps(matricula text primary
key,color text,talla text)";
String sql2 = "create table if not exists alumnos(matricula text primary
key,nombre text,tel text)";
Log.d("Data", "onCreate: " + sql1);
Log.d("Data", "onCreate: " + sql2);
db.execSQL(sql1);
db.execSQL(sql2);
}
}
我真的不明白这里的问题;请至少发布您的LogCat输出,并指出代码在哪一行崩溃(如果确实崩溃)。