要实现android studio中简单的实现增删查改,创建一个数据模型类,如何对应数据库中的表结构
时间: 2024-05-21 17:13:06 浏览: 12
你可以使用ORM框架,如Room或GreenDAO,来简化数据库操作。首先创建一个数据模型类,并使用注解来描述与数据库中的表结构的对应关系。例如,使用@Entity注解将类标记为实体,在该注解中指定实体对应的表名;使用@PrimaryKey注解指定主键字段,使用@Column注解指定字段名等。接下来,使用相应的注解配置数据库版本号、表名、字段名等信息,并编写相应的DAO操作方法来实现增删查改等数据库操作。
相关问题
android studio中简单的实现增删查改的代码
以下是一个简单的实现增删查改的代码实例:
增加数据:
```
public boolean addData(String name, String email, String phone) {
SQLiteDatabase db = this.getWritableDatabase();
ContentValues contentValues = new ContentValues();
contentValues.put(COL_NAME, name);
contentValues.put(COL_EMAIL, email);
contentValues.put(COL_PHONE, phone);
long result = db.insert(TABLE_NAME, null, contentValues);
if (result == -1) {
return false;
} else {
return true;
}
}
```
删除数据:
```
public Integer deleteData(String id) {
SQLiteDatabase db = this.getWritableDatabase();
return db.delete(TABLE_NAME, "ID = ?", new String[] { id });
}
```
更新数据:
```
public boolean updateData(String id, String name, String email, String phone) {
SQLiteDatabase db = this.getWritableDatabase();
ContentValues contentValues = new ContentValues();
contentValues.put(COL_ID, id);
contentValues.put(COL_NAME, name);
contentValues.put(COL_EMAIL, email);
contentValues.put(COL_PHONE, phone);
db.update(TABLE_NAME, contentValues, "ID = ?", new String[] { id });
return true;
}
```
查询数据:
```
public Cursor getData() {
SQLiteDatabase db = this.getWritableDatabase();
String query = "SELECT * FROM " + TABLE_NAME;
Cursor data = db.rawQuery(query, null);
return data;
}
```
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Android studio中的SQL数据库的增删查改
在 Android Studio 中,可以使用 SQLite 数据库进行数据存储和管理。下面是使用 SQL 数据库进行增删查改的示例代码:
## 建表
```java
public class MyDatabaseHelper extends SQLiteOpenHelper {
private static final String DB_NAME = "my_database";
private static final int DB_VERSION = 1;
private static final String TABLE_NAME = "my_table";
private static final String COLUMN_ID = "_id";
private static final String COLUMN_NAME = "name";
private static final String COLUMN_AGE = "age";
public MyDatabaseHelper(Context context) {
super(context, DB_NAME, null, DB_VERSION);
}
@Override
public void onCreate(SQLiteDatabase db) {
String createTableSql = "CREATE TABLE " + TABLE_NAME + " ("
+ COLUMN_ID + " INTEGER PRIMARY KEY AUTOINCREMENT,"
+ COLUMN_NAME + " TEXT,"
+ COLUMN_AGE + " INTEGER)";
db.execSQL(createTableSql);
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
String dropTableSql = "DROP TABLE IF EXISTS " + TABLE_NAME;
db.execSQL(dropTableSql);
onCreate(db);
}
}
```
## 插入数据
```java
public class MainActivity extends AppCompatActivity {
private MyDatabaseHelper dbHelper;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
dbHelper = new MyDatabaseHelper(this);
SQLiteDatabase db = dbHelper.getWritableDatabase();
ContentValues values = new ContentValues();
values.put(MyDatabaseHelper.COLUMN_NAME, "张三");
values.put(MyDatabaseHelper.COLUMN_AGE, 18);
db.insert(MyDatabaseHelper.TABLE_NAME, null, values);
db.close();
}
}
```
## 查询数据
```java
public class MainActivity extends AppCompatActivity {
private MyDatabaseHelper dbHelper;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
dbHelper = new MyDatabaseHelper(this);
SQLiteDatabase db = dbHelper.getReadableDatabase();
Cursor cursor = db.query(MyDatabaseHelper.TABLE_NAME, null, null, null, null, null, null);
while (cursor.moveToNext()) {
int id = cursor.getInt(cursor.getColumnIndex(MyDatabaseHelper.COLUMN_ID));
String name = cursor.getString(cursor.getColumnIndex(MyDatabaseHelper.COLUMN_NAME));
int age = cursor.getInt(cursor.getColumnIndex(MyDatabaseHelper.COLUMN_AGE));
Log.d("MainActivity", "id=" + id + ", name=" + name + ", age=" + age);
}
cursor.close();
db.close();
}
}
```
## 更新数据
```java
public class MainActivity extends AppCompatActivity {
private MyDatabaseHelper dbHelper;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
dbHelper = new MyDatabaseHelper(this);
SQLiteDatabase db = dbHelper.getWritableDatabase();
ContentValues values = new ContentValues();
values.put(MyDatabaseHelper.COLUMN_AGE, 20);
db.update(MyDatabaseHelper.TABLE_NAME, values, MyDatabaseHelper.COLUMN_NAME + "=?", new String[]{"张三"});
db.close();
}
}
```
## 删除数据
```java
public class MainActivity extends AppCompatActivity {
private MyDatabaseHelper dbHelper;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
dbHelper = new MyDatabaseHelper(this);
SQLiteDatabase db = dbHelper.getWritableDatabase();
db.delete(MyDatabaseHelper.TABLE_NAME, MyDatabaseHelper.COLUMN_NAME + "=?", new String[]{"张三"});
db.close();
}
}
```
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