在删除行时出现异常

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我有一个Sqlite数据库，我将它限制为最多10行的最新条目。逻辑是插入任何新条目时，我检查行数。如果已经有10行，它将删除最早的输入行并添加一个新行。但是我收到错误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？在删除行时出现异常

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"); 
}

}

来源

2016-12-31 Somnath Pal

的'LIMIT'子句不能用'DELETE'使用。顺便说一下，前几天你没有问过类似的问题吗？ –

只需在'ORDER BY'前后放置空格。 –

'String DELETE_ROW =“DELETE FROM”+ TABLE_PROF +“ORDER BY”+ KEY_ID +“LIMIT 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";

只要把空间之前和之后ORDER BY。

而@TimBiegeleisen指出，LIMIT子句不适用于DELETE。

一个解决办法是这样的 -

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

来源

2016-12-31 08:36:38

是的，我认为LIMIT不会与DELETE一起工作，因为我在'ORDER附近'出现异常：语法错误（代码1）：'@Shreyash –

也检查此链接（http://stackoverflow.com/问题/ 31619424/delete-all-top-n-from-database-table-in-sqlite-for-java-android），因为这也显示了类似的逻辑 –

这里的someColumn是什么？我可以使用任何列名称（如KEY_NAME）删除第一行吗？ –

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";

这样。请注意ORDER之前和BY之后的空间。

来源

2016-12-31 08:32:00 muthuraj

在删除行时出现异常

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