安卓 数据库使用
摘要：数据库一无所知，最近用到，百度+问群，刚刚入门，自己总结一下做个笔记：1，创建数据库：继承SQLiteOpenHelperpubliccla...
数据库一无所知，最近用到，百度+问群，刚刚入门，自己总结一下做个笔记：
1，创建数据库：继承SQLiteOpenHelper
public class DatabaseHelper extends SQLiteOpenHelper {
private String Tag = "DatabaseHelper";
public DatabaseHelper(Context context, String name,
CursorFactory factory, int version) {
super(context, name, factory, version);
// TODO Auto-generated constructor stub
}
@Override
public void onCreate(SQLiteDatabase db) {
// TODO Auto-generated method stub
LogUtils.i(Tag, "onCreate");
try {
//本机处理操作同步到云端后的记录
db.execSQL("CREATE TABLE devicesOperation_tb ("
+ "directory VARCHAR (50) NOT NULL,"
+ "rootDir VARCHAR (20) NOT NULL,"
+ "parentDir VARCHAR (20) NOT NULL,"
+ "fileName VARCHAR (50) NOT NULL,"
+ "time VARCHAR (50) NOT NULL"
+ ");");
//本机所有文件记录，用于和操作后的对比，devicesFile_tb记录没有，devicesOperation_tb记录有的话，则是删除操作
db.execSQL("CREATE TABLE devicesFile_tb ("
+ "directory VARCHAR (50) NOT NULL,"
+ "rootDir VARCHAR (20) NOT NULL,"
+ "parentDir VARCHAR (20) NOT NULL,"
+ "fileName VARCHAR (50) NOT NULL,"
+ "time VARCHAR (50) NOT NULL"
+ ");");
//云端操作记录表
db.execSQL("CREATE TABLE serverOperation_tb ("
+ "fileName VARCHAR (50) NOT NULL,"
+ "rootDir VARCHAR (20) NOT NULL,"
+ "parentDir VARCHAR (20) NOT NULL,"
+ "operation VARCHAR (10) NOT NULL,"
+ "filePath VARCHAR (100)"
+ ");");
} catch (Exception e) {
// TODO: handle exception
LogUtils.i(Tag, "onCreate:"+e);
}
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
// TODO Auto-generated method stub
}
}
db.execSQL("CREATE TABLE devicesOperation_tb ("
+ "directory VARCHAR (50) NOT NULL,"
+ "rootDir VARCHAR (20) NOT NULL,"
+ "parentDir VARCHAR (20) NOT NULL,"
+ "fileName VARCHAR (50) NOT NULL,"
+ "time VARCHAR (50) NOT NULL"
+ ");");这一句是创建数据库， devicesOperation_tb：表名；后面都是字段名，每一句以“，”逗号结束，最后一句不用
2，获取执行创建数据库，得到数据库：
mDatabaseHelper = new DatabaseHelper(mContext, DATABASE_NAME, null, 1); mSqLiteDatabase = mDatabaseHelper.getReadableDatabase();只new是得不到数据库的，必须要get ReadableDatabase()或者getWriteableDatabase()一下才能看到数据库，这句执行后，就可以在data/data/你的项目包名/databases下面看到有一个 devicesOperation_tb.db的数据库了
3，数据库添加数据，也就是insert语句：
ContentValues cv = new ContentValues();
cv.put(DevicesOperationTB.directory, f.toString());
cv.put(DevicesOperationTB.rootDir, FilePath.split("/")[0]);
cv.put(DevicesOperationTB.parentDir, FilePath.split("/")[1]);cv.put(DevicesOperationTB.fileName, FilePath.split("/")[2]);mSqLiteDatabase.insert(DevicesFileTB.devicesFile_tb, null, cv);
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