我使用以下代码创建表并将数据插入表中。代码仅在select语句位于同一文件中时显示数据。我注意到/ data / data中没有数据库。我错过了一些东西或者这个过程实际上是错的吗？如果错了那我该怎么办？
surgicalmstDB = this.openOrCreateDatabase("surgicalmstDB ", SQLiteDatabase.CREATE_IF_NECESSARY, null);
surgicalmstDB.setVersion(1);
surgicalmstDB.setLocale(Locale.getDefault());
surgicalmstDB.setLockingEnabled(true);
surgicalmstDB.execSQL("CREATE TABLE IF NOT EXISTS " +
" instrument " +
" (id int,instrumnt TEXT, category TEXT, details TEXT);");
surgicalmstDB.execSQL("INSERT INTO " +
"instrument" +
" Values (2,'#3 Long Knife Handle ','Cutting and dissecting','Used to cut deeper tissue.');");
//-----------------------------------------------------------------
String query="SELECT * from instrument WHERE id=2";
Cursor cursor=surgicalmstDB.rawQuery(query, null);
while (cursor.moveToNext()) {
String title =cursor.getString(cursor
.getColumnIndex("instrumnt"));
String author= cursor.getString(cursor
.getColumnIndex("category"));
String price= cursor.getString(cursor
.getColumnIndex("details"));
txt.setText(title+"-----"+author+"-------"+price);
}
cursor.close();
surgicalmstDB.close();
答案 0 :(得分：1)
我建议你引用SQLiteOpenHelper而不是硬编码查询。
以下代码可以帮助您
员工模型类
package com.database;
public class Employee {
int _id;
String _name;
String _phone_number;
public Employee (){
}
// constructor
public Employee (int id, String name, String _phone_number){
this._id = id;
this._name = name;
this._phone_number = _phone_number;
}
// constructor
public Employee (String name, String _phone_number){
this._name = name;
this._phone_number = _phone_number;
}
// getting ID
public int getID(){
return this._id;
}
// setting id
public void setID(int id){
this._id = id;
}
// getting name
public String getName(){
return this._name;
}
// setting name
public void setName(String name){
this._name = name;
}
// getting phone number
public String getPhoneNumber(){
return this._phone_number;
}
// setting phone number
public void setPhoneNumber(String phone_number){
this._phone_number = phone_number;
}
}
SQLite帮助程序类
公共类DatabaseHelper扩展了SQLiteOpenHelper {
private static final int DATABASE_VERSION = 1;
private static final String DATABASE_NAME = "employeeDB";
private static final String TABLE_EMPLOYEE = "employee";
private static final String KEY_ID = "id";
private static final String KEY_NAME = "name";
private static final String KEY_PH_NO = "phone_number";
public DatabaseHelper (Context context) {
super(context, DATABASE_NAME, null, DATABASE_VERSION);
}
// Creating Tables
@Override
public void onCreate(SQLiteDatabase db) {
String CREATE_CONTACTS_TABLE = "CREATE TABLE " + TABLE_EMPLOYEE + "("
+ KEY_ID + " INTEGER PRIMARY KEY," + KEY_NAME + " TEXT,"
+ KEY_PH_NO + " TEXT" + ")";
db.execSQL(CREATE_CONTACTS_TABLE);
}
// Upgrading database
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
// Drop older table if existed
db.execSQL("DROP TABLE IF EXISTS " + TABLE_CONTACTS);
// Create tables again
onCreate(db);
}
CRUD操作
// 添加新员工
public void addEmployee(Employee employee) {}
// 获取单个员工
public Contact getEmployee(int id) {}
// 获取所有员工
public List<Employee> getAllEmployees() {}
// 让员工重要
public int getEmployeesCount() {}
// 更新单个员工
public int updateEmployee(Employee employee) {}
// 删除单个员工
public void deleteEmployee(Employee employee) {}
插入新记录
public void addemployee(Employee employee) {
SQLiteDatabase db = this.getWritableDatabase();
ContentValues values = new ContentValues();
values.put(KEY_NAME, employee.getName());
values.put(KEY_PH_NO, employee.getPhoneNumber());
db.insert(TABLE_EMPLOYEE, null, values);
db.close();
}
阅读行
public Contact getEmployee(int id) {
SQLiteDatabase db = this.getReadableDatabase();
Cursor cursor = db.query(TABLE_EMPLOYEE, new String[] { KEY_ID,
KEY_NAME, KEY_PH_NO }, KEY_ID + "=?",
new String[] { String.valueOf(id) }, null, null, null, null);
if (cursor != null)
cursor.moveToFirst();
Employee employee= new Employee(Integer.parseInt(cursor.getString(0)),
cursor.getString(1), cursor.getString(2));
return employee;
}
获取所有员工
public List<Contact> getAllEmployees() {
List<Employee> employeeList = new ArrayList<Employee>();
// Select All Query
String selectQuery = "SELECT * FROM " + TABLE_EMPLOYEE;
SQLiteDatabase db = this.getWritableDatabase();
Cursor cursor = db.rawQuery(selectQuery, null);
// looping through all rows and adding to list
if (cursor.moveToFirst()) {
do {
Employee employee= new Employee();
employee.setID(Integer.parseInt(cursor.getString(0)));
employee.setName(cursor.getString(1));
employee.setPhoneNumber(cursor.getString(2));
employeeList.add(employee);
} while (cursor.moveToNext());
}
return employeeList;
}
获取所有员工数
public int getEmployeesCount() {
String countQuery = "SELECT * FROM " + TABLE_EMPLOYEE;
SQLiteDatabase db = this.getReadableDatabase();
Cursor cursor = db.rawQuery(countQuery, null);
cursor.close();
// return count
return cursor.getCount();
}
更新记录
public int updateEmployee(Employee employee) {
SQLiteDatabase db = this.getWritableDatabase();
ContentValues values = new ContentValues();
values.put(KEY_NAME, employee.getName());
values.put(KEY_PH_NO, employee.getPhoneNumber());
// updating row
return db.update(TABLE_EMPLOYEE, values, KEY_ID + " = ?",
new String[] { String.valueOf(employee.getID()) });
}
删除记录
public void deleteEmployee(Employee employee) {
SQLiteDatabase db = this.getWritableDatabase();
db.delete(TABLE_EMPLOYEE, KEY_ID + " = ?",
new String[] { String.valueOf(employee.getID()) });
db.close();
}
答案 1 :(得分：0)
请参阅此示例，我们有明确的想法Android SQLite Database and ContentProvider - Tutorial
答案 2 :(得分：0)
您可以使用simple approach并测试我的样本SQLite database project。