Question

我有一个Sqlite数据库，我将其限制为最多10行最新条目。逻辑是在插入任何新条目时我检查行数。如果已有10行，则会删除最早输入的行并添加新行。但我收到错误SQLiteException: near "BYid": syntax error (code 1): , while compiling: DELETE FROM profORDER BYid LIMIT 1。这是因为任何空间不匹配或查询错误吗？

public class SQLiteHandler extends SQLiteOpenHelper {

private static final String TAG = SQLiteHandler.class.getSimpleName();

// All Static variables
// Database Version
private static final int DATABASE_VERSION = 1;

// Database Name
private static final String DATABASE_NAME = "android_api";

// Profile Settings table name
private static final String TABLE_PROF = "prof";

// Profile Settings information names
private static final String KEY_ID = "id";
private static final String KEY_NAME = "name";
private static final String KEY_MOBILE = "mobile";


public SQLiteHandler(Context context) {
    super(context, DATABASE_NAME, null, DATABASE_VERSION);
}

// Creating Tables
@Override
public void onCreate(SQLiteDatabase db) {

    String CREATE_PROF_TABLE = "CREATE TABLE " + TABLE_PROF + "("+KEY_ID+" INTEGER PRIMARY KEY, "+KEY_NAME+" TEXT,  "+KEY_MOBILE+" TEXT" + ")";

    db.execSQL(CREATE_PROF_TABLE);

    Log.d(TAG, "Database tables created");
}

// Upgrading database
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
    // Drop older table if existed
    db.execSQL("DROP TABLE IF EXISTS " + TABLE_PROF);

    // Create tables again
    onCreate(db);
}


/**
 * Storing Prof_settings details in database
 * */
public void addProfile(String name, String mobile){

    SQLiteDatabase db = this.getWritableDatabase();

    ContentValues values = new ContentValues();

    values.put(KEY_NAME, name);
    values.put(KEY_MOBILE, mobile);

    int count = getProfilesCount();

    if(count == 10) {

        String DELETE_ROW = "DELETE FROM " +TABLE_PROF+ "ORDER BY" +KEY_ID+" LIMIT 1";

        db.execSQL(DELETE_ROW); // will delete oldest record
    }

    long id = db.insert(TABLE_PROF, null, values); // insert to 1st row
    db.close(); // Closing database connection

    Log.d(TAG, "New profile settings inserted into sqlite: " + id);

}




/**
 * Getting Profile Settings data from database
 * */
public ArrayList<HashMap<String, String>> getProfDetails()
{
    ArrayList<HashMap<String, String>> array_list = new ArrayList<HashMap<String, String>>();

    SQLiteDatabase db = this.getReadableDatabase();
    //Cursor res = db.rawQuery("SELECT * " + " FROM " + TABLE_PROF + " GROUP BY " + KEY_NAME + " ORDER BY " + KEY_MOBILE + " COLLATE NOCASE;", null);
    String selectQuery = "SELECT  * FROM " + TABLE_PROF;
    Cursor res = db.rawQuery(selectQuery, null);
    res.moveToFirst();

    while (res.isAfterLast() == false)
    {
        HashMap<String, String> hashmap= new HashMap<String, String>();
        hashmap.put("id", res.getString(res.getColumnIndex(KEY_ID)));
        hashmap.put("name", res.getString(res.getColumnIndex(KEY_NAME)));
        hashmap.put("mobile", res.getString(res.getColumnIndex(KEY_MOBILE)));

        array_list.add(hashmap);
        res.moveToNext();
    }
    return array_list;
}

public int getProfilesCount() {
    String countQuery = "SELECT  * FROM " + TABLE_PROF;
    SQLiteDatabase db = this.getReadableDatabase();
    Cursor cursor = db.rawQuery(countQuery, null);
    int cnt = cursor.getCount();
    cursor.close();
    return cnt;
}

/**
 * Re crate database Delete all tables and create them again
 * */
public void deleteUsers() {
    SQLiteDatabase db = this.getWritableDatabase();
    // Delete All Rows
    db.delete(TABLE_PROF, null, null);
    db.close();

    Log.d(TAG, "Deleted all profile info from sqlite");
}

}

Answer 1

更改此

"DELETE FROM " +TABLE_PROF+ "ORDER BY" +KEY_ID+" LIMIT 1";

到

"DELETE FROM " +TABLE_PROF+ " ORDER BY " +KEY_ID+" LIMIT 1";

只需在ORDER BY之前和之后放置空格。

正如@TimBiegeleisen指出的那样，LIMIT子句不适用于DELETE。

这是一个解决方法 -

"DELETE FROM " + TABLE_PROF
+ " WHERE someColumn in ( "
+ "    SELECT someColumn FROM " + TABLE_PROF + " ORDER BY " + KEY_ID + " LIMIT 1"
+ ")";

Answer 2

String DELETE_ROW = "DELETE FROM " +TABLE_PROF+ "ORDER BY" +KEY_ID+" LIMIT 1";

这应该是

String DELETE_ROW = "DELETE FROM " +TABLE_PROF+ " ORDER BY " +KEY_ID+" LIMIT 1";

像这样。注意ORDER之前和BY之后的空格。

删除行时出现异常

2 个答案: