我最近在Android应用商店中推出了一个包含SQLite数据库的应用程序。
我现在正在尝试发布应用程序的更新，并希望在现有数据库中添加更多数据，但是有点不紧张。我已阅读有关SO的答案，其中概述了对数据库本身的更改，但我希望我的表和列保持不变，只需添加新数据。
我想要添加到数据库的数据是从Raw文件中的CSV文件中提取的，并且在用户注册该应用程序时最初加载到数据库中。
我有一种感觉，我需要实现onUpgrade方法，但是我是否应该在此时添加CSV文件中的新数据？是简单更新数据库版本并使用onUpgrade加载新数据吗？
我对SQLite DB很新，所以任何帮助都会非常受欢迎。
CourseDBHelper代码
public class CourseDBHelper extends SQLiteOpenHelper {
// Database Version
private static final int DATABASE_VERSION = 1;
// Database Name
private static final String DATABASE_NAME = "CourseDB";
// Create two table names
private static final String TABLE_COURSES = "courses";
// Universities Table Columns names
private static final String COURSE_NAME = "Course_name";
private static final String UNI_NAME = "Uni_name";
private static final String COURSE_DURATION = "Duration";
private static final String COURSE_STUDY_MODE = "Study_mode";
private static final String COURSE_QUALIFICATION = "Qualification";
private static final String COURSE_ENTRY_STANDARDS = "Entry_standards";
private static final String COURSE_GRADUATE_PROSPECTS = "Graduate_prospects";
private static final String COURSE_STUDENT_SATISFACTION = "Student_satisfaction";
private String CREATE_COURSES_TABLE = "CREATE TABLE courses" +
"(" +
"_id INTEGER PRIMARY KEY AUTOINCREMENT," +
"Course_name TEXT NOT NULL," +
"Uni_name TEXT NOT NULL," +
"Duration TEXT NOT NULL," +
"Study_mode TEXT NOT NULL," +
"Qualification TEXT NOT NULL," +
"Entry_standards TEXT NOT NULL," +
"Graduate_prospects TEXT NOT NULL," +
"Student_satisfaction TEXT NOT NULL" +
");";
private static final String[] COLUMNS = {
COURSE_NAME,
UNI_NAME,
COURSE_DURATION,
COURSE_STUDY_MODE,
COURSE_QUALIFICATION,
COURSE_ENTRY_STANDARDS,
COURSE_GRADUATE_PROSPECTS,
COURSE_STUDENT_SATISFACTION
};
public CourseDBHelper(Context context)
{
super(context, DATABASE_NAME, null, DATABASE_VERSION);
}
// TODO: REMOVED NOT NULL FROM EVERY COLUMN FOR TEST PURPOSES, WILL NEED TO BE READDED
@Override
public void onCreate(SQLiteDatabase db)
{
db.execSQL(CREATE_COURSES_TABLE);
}
public void deleteAll()
{
SQLiteDatabase db = this.getWritableDatabase();
db.delete("courses", null, null);
db.execSQL("delete from " + "courses");
db.close();
}
// Getting one course by course name and uni name
public Course getCourse(String courseName, String uniName) {
SQLiteDatabase db = this.getReadableDatabase();
Cursor cursor = db.query(TABLE_COURSES, COLUMNS, " Course_name = ? AND Uni_name = ?",
new String[]{courseName, uniName},
null,
null,
null,
null);
if (cursor != null)
cursor.moveToFirst();
Course course = new Course();
/*
System.out.println(cursor.getString(0));
System.out.println(cursor.getString(1));
System.out.println(cursor.getString(2));
System.out.println(cursor.getString(3));
System.out.println(cursor.getString(4));
System.out.println(cursor.getString(5));
System.out.println(cursor.getString(6));
*/
course.setCourseName(cursor.getString(0));
course.setUniversity(cursor.getString(1));
course.setCourseDuration(cursor.getString(2));
course.setStudyMode(cursor.getString(3));
course.setQualification(cursor.getString(4));
course.setEntryStandards(cursor.getString(5));
course.setGradProspects(cursor.getString(6));
course.setStudentSatisfaction(cursor.getString(7));
return course;
}
public void addCourse(Course course)
{
SQLiteDatabase db = this.getWritableDatabase();
ContentValues values = new ContentValues();
values.put(COURSE_NAME, course.getCourseName());
values.put(UNI_NAME, course.getUniversity());
values.put(COURSE_DURATION, course.getCourseDuration());
values.put(COURSE_STUDY_MODE, course.getStudyMode());
values.put(COURSE_QUALIFICATION, course.getQualification());
values.put(COURSE_ENTRY_STANDARDS, course.getEntryStandards());
values.put(COURSE_GRADUATE_PROSPECTS, course.getGradProspects());
values.put(COURSE_STUDENT_SATISFACTION, course.getStudentSatisfaction());
db.insert(TABLE_COURSES,
null, //nullColumnHack
values);
db.close();
}
public ArrayList<Course> getAllCourses()
{
ArrayList<Course> courses = new ArrayList<>();
// 1. build the query
String query = "SELECT * FROM " + TABLE_COURSES;
// 2. get reference to writable DB
SQLiteDatabase db = this.getWritableDatabase();
Cursor cursor = db.rawQuery(query, null);
// 3. go over each row, build course and add it to list
Course course;
if(cursor.moveToFirst()){
cursor.moveToNext();
do{
course = new Course();
course.setCourseName(cursor.getString(1));
course.setUniversity(cursor.getString(2));
course.setCourseDuration(cursor.getString(3));
course.setStudyMode(cursor.getString(4));
course.setQualification(cursor.getString(5));
course.setEntryStandards(cursor.getString(6));
course.setGradProspects(cursor.getString(7));
course.setStudentSatisfaction(cursor.getString(8));
// Add course to courses list
courses.add(course);
} while(cursor.moveToNext());
}
// return courses
return courses;
}
public int getDBCount()
{
SQLiteDatabase db = this.getWritableDatabase();
String count = "SELECT count(*) FROM courses";
Cursor mcursor = db.rawQuery(count, null);
mcursor.moveToFirst();
int icount = mcursor.getInt(0);
return icount;
}
public void deleteCourse(Course course) {
// 1. get reference to writable DB
SQLiteDatabase db = this.getWritableDatabase();
// 2. delete
db.delete("courses", //table name
"Course_name = ? AND Uni_name = ?", // selections
new String[] { course.getCourseName(), course.getUniversity() }); //selections args
// 3. close
db.close();
}
@Override
public void onUpgrade(SQLiteDatabase sqLiteDatabase, int i, int i1) {
}
}
将数据从CSV文件加载到SQlite DB
的方法public void populateCourseDatabase(int id) {
// NOW POPULATE THE COURSE DATABASE FILE
inputStream = getResources().openRawResource(R.raw.coursesone);
BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream));
String word;
String cvsSplitBy = ",";
try{
while((word = reader.readLine()) != null){
Log.d(TAG, "constructing Course object from: " + word);
String[] segment = word.split(cvsSplitBy);
Course course = new Course();
course.setCourseName(segment[0]);
course.setUniversity(segment[1]);
course.setCourseDuration(segment[2]);
course.setStudyMode(segment[3]);
course.setQualification(segment[4]);
course.setEntryStandards(segment[5]);
course.setGradProspects(segment[6]);
course.setStudentSatisfaction(segment[7]);
myCourseDBHelper.addCourse(course);
progressBar.setProgress(count);
count = count + 1;
System.out.println("Sucessfully added: " + course.toString());
}
}
catch(IOException e1){
e1.printStackTrace();
System.out.println("SOMETHING WENT WRONG");
}
}
答案 0 :(得分：1)
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
switch(oldVersion) {
case 1:
//upgrade logic from version 1 to 2
case 2:
//upgrade logic from version 2 to 3
case 3:
//upgrade logic from version 3 to 4
break;
default:
throw new IllegalStateException(
"onUpgrade() with unknown oldVersion " + oldVersion);
}
}