插入数据库时​​没有此类表格异常

Question

我正在研究一个简单的空气质量控制应用程序。我需要使用SQLite存储空气质量测量结果。我创建了扩展SQLiteOpenHelper类的db helper类。它应该创建一个表measurements。

public class SmogDbHelper extends SQLiteOpenHelper { 

    private static final int DATABASE_VERSION = 1; 

    public static final String DATABASE_NAME = "smog.db"; 

    interface Tables { 
     String MEASUREMENT = "measurement"; 
    } 

    interface Triggers { 
     String ON_MEASUREMENT_INSERTED = "on_measurement_inserted"; 
    } 

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

    @Override 
    public void onCreate(SQLiteDatabase db) { 

     final String SQL_CREATE_TABLE_MEASUREMENT = 
       "CREATE TABLE " + Tables.MEASUREMENT + " (" + MeasurementEntry._ID + 
       " INTEGER PRIMARY KEY, " + 
       MeasurementEntry.COLUMN_LONGITUDE + " REAL NOT NULL, " + 
       MeasurementEntry.COLUMN_LATITUDE + " REAL NOT NULL, " + 
       MeasurementEntry.COLUMN_FROM_DATE_TIME + " INTEGER NOT NULL, " + 
       MeasurementEntry.COLUMN_TILL_DATE_TIME + " INTEGER, " + 
       MeasurementEntry.COLUMN_PM_1 + " REAL NOT NULL, " + 
       MeasurementEntry.COLUMN_PM_25 + " REAL NOT NULL, " + 
       MeasurementEntry.COLUMN_PM_10 + " REAL NOT NULL, " + 
       MeasurementEntry.COLUMN_POLUTION_LEVEL + " INTEGER NOT NULL, " + 
       MeasurementEntry.COLUMN_AIR_QUALITY_INDEX + " REAL NOT NULL, " + 
       MeasurementEntry.COLUMN_SOURCE + " TEXT NOT NULL" + 
       ");"; 

     final String SQL_CREATE_ON_MEASUREMENT_INSERTED_TRIGGER = "CREATE TRIGGER " + Triggers.ON_MEASUREMENT_INSERTED + 
       " AFTER INSERT ON " + Tables.MEASUREMENT + 
       " BEGIN " + 
       "DELETE FROM LOG WHERE " + MeasurementEntry.COLUMN_FROM_DATE_TIME + " < " + 
       "(strftime('%s', 'now') - 604800);\n" + 
       " END;"; 

     db.execSQL(SQL_CREATE_TABLE_MEASUREMENT); 
     db.execSQL(SQL_CREATE_ON_MEASUREMENT_INSERTED_TRIGGER); 
    } 

    @Override 
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) { 
     db.execSQL("DROP TABLE IF EXISTS " + Tables.MEASUREMENT); 
     db.execSQL("DROP TRIGGER IF EXISTS " + Triggers.ON_MEASUREMENT_INSERTED); 
    } 
} 

并使用以下单元测试进行测试。

@RunWith(AndroidJUnit4.class) 
@LargeTest 
public class TestDb { 

    private static final String LOG_TAG = "TestDb"; 
    private SmogDbHelper smogDbHelper; 
    private SQLiteDatabase db; 

    // remove old database if present before starting tests 
    @Before 
    public void setUp() throws Exception { 
     getTargetContext().deleteDatabase(SmogDbHelper.DATABASE_NAME); 
     smogDbHelper = new SmogDbHelper(getTargetContext()); 
     db = smogDbHelper.getWritableDatabase(); 
    } 

    @After 
    public void tearDown() throws Exception { 
     db.close(); 
    } 

    @Test 
    public void testTableCreation() { 

     Assert.assertEquals(true, db.isOpen()); 

     // hash set of all tables we are looking for in the db 
     final HashSet<String> tableNameHashSet = new HashSet<String>(); 
     tableNameHashSet.add(SmogContract.MeasurementEntry.TABLE_NAME); 

     Cursor c = db.rawQuery("SELECT name FROM sqlite_master WHERE type ='table'", null); 

     Assert.assertTrue("Error: This means that the database has not been created correctly", 
       c.moveToFirst()); 

     // remove all table names from hash map which are in db. 
     do { 
      String tableName = c.getString(0); 
      Log.v(LOG_TAG, tableName); 
      tableNameHashSet.remove(tableName); 
     } while (c.moveToNext()); 

     c.close(); 
     // if this fails not all tables have been created correctly 
     Assert.assertTrue("Error: Your database is missing " + tableNameHashSet.size() 
       + " tables.", tableNameHashSet.isEmpty()); 

     c = db.rawQuery("PRAGMA table_info(" + SmogContract.MeasurementEntry.TABLE_NAME + ")", 
       null); 

     Assert.assertTrue("Error: Unable to query the database for table information.", 
       c.moveToFirst()); 

     // all columns we want to look for in MeasurementEntry 
     final HashSet<String> measurementColumnHashSet = new HashSet<String>(); 
     measurementColumnHashSet.add(SmogContract.MeasurementEntry._ID); 
     measurementColumnHashSet.add(SmogContract.MeasurementEntry.COLUMN_AIR_QUALITY_INDEX); 
     measurementColumnHashSet.add(SmogContract.MeasurementEntry.COLUMN_FROM_DATE_TIME); 
     measurementColumnHashSet.add(SmogContract.MeasurementEntry.COLUMN_TILL_DATE_TIME); 
     measurementColumnHashSet.add(SmogContract.MeasurementEntry.COLUMN_LATITUDE); 
     measurementColumnHashSet.add(SmogContract.MeasurementEntry.COLUMN_LONGITUDE); 
     measurementColumnHashSet.add(SmogContract.MeasurementEntry.COLUMN_PM_1); 
     measurementColumnHashSet.add(SmogContract.MeasurementEntry.COLUMN_PM_25); 
     measurementColumnHashSet.add(SmogContract.MeasurementEntry.COLUMN_PM_10); 
     measurementColumnHashSet.add(SmogContract.MeasurementEntry.COLUMN_SOURCE); 
     measurementColumnHashSet.add(SmogContract.MeasurementEntry.COLUMN_POLUTION_LEVEL); 

     int columnNameIndex = c.getColumnIndex("name"); 
     do { 
      String columnName = c.getString(columnNameIndex); 
      Log.v(LOG_TAG, columnName); 
      measurementColumnHashSet.remove(columnName); 
     } while (c.moveToNext()); 

     Assert.assertTrue("Error: The database doesn't contain all of the required location entry columns", 
       measurementColumnHashSet.isEmpty()); 

     c.close(); 
    } 

    @Test 
    public void testMeasurementTable() { 

     ContentValues measurementValues = TestUtilities.createMeasurementValues(); 
     long measurementRowId = db.insert(SmogContract.MeasurementEntry.TABLE_NAME, 
       null, measurementValues); 
     Assert.assertTrue(measurementRowId != -1); 

     Cursor measurementCursor = db.query(
       SmogContract.MeasurementEntry.TABLE_NAME, 
       null, null, null, null, null, null 
     ); 
     Assert.assertTrue("Error: No Records returned from location query", 
       measurementCursor.moveToFirst()); 

     measurementCursor.close(); 
    } 

} 

虽然测试表创建工作正常运行插入和查询测试我得到以下异常。

android.database.sqlite.SQLiteException: no such table: main.LOG (code 1): , while compiling: INSERT INTO measurement(pm_25,from_date_time,pm_10,polution_level,source,till_date_time,air_quality_index,longitude,latitude,pm_1) VALUES (?,?,?,?,?,?,?,?,?,?) 

我对什么可能会导致此问题不知情。任何帮助或建议，一如既往，非常感谢。

Answer 1

触发说：

DELETE FROM LOG ... 

但有没有这样的表。

您可能想从同一张表中删除。