只有一个表创建了sql Lite Android

时间：2018-12-12 02:13:34

标签： android android-sqlite

我将使用DataHelper.java创建一个表，但仅创建一个表（位置表），这里是我的代码

public class DataHelper extends SQLiteOpenHelper {

    private static final String LOGCAT = null;
    private static final String DATABASE_NAME = "layerfarm-mobile.db";
    private static final int DATABASE_VERSION = 1;

    public static final String locationSQL = "CREATE TABLE IF NOT EXISTS location(id integer primary key, name text, address text, rid integer);";
    public static final String eqq_qualitySQL = "CREATE TABLE IF NOT EXISTS  eqq_quality(id integer primary key, name text);";

    public DataHelper(Context context) {
        super(context, DATABASE_NAME, null, DATABASE_VERSION);
        Log.d(LOGCAT,"Created");
        // TODO Auto-generated constructor stub
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        try {
            //Create table
            db.execSQL(locationSQL);
            db.execSQL(eqq_qualitySQL);

        String InsertlocationSQL = "INSERT INTO location (id, name, address, rid) VALUES " +
                "(1,'Location A','Blitar',1)," +
                "(2,'Location B','Blitar',2)," +
                "(3,'Location C','Blitar',3)," +
                "(4,'Location D','Blitar',4);";
        db.execSQL(InsertlocationSQL);

        String InsertEggQualitySQL = "INSERT INTO egg_quality (id, name) VALUES " +
                "(1,'Quality A'), " +
                "(2,'Quality B'), " +
                "(3,'Quality C'), " +
                "(4,'Cracked');";
        db.execSQL(InsertEggQualitySQL);
        }catch (Exception e){
            e.printStackTrace();
        }
    }


    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {

        // Drop table if existed, all data will be gone!!!
        db.execSQL("DROP TABLE IF EXISTS location;"); 
    db.execSQL("DROP TABLE IF EXISTS eqq_quality;"); onCreate(db);
    }

}

创建表并为位置表插入成功，但其他表失败，错误日志显示在此处：

 Caused by: android.database.sqlite.SQLiteException: no such table: 
 egg_quality (code 1): , while compiling: SELECT * FROM egg_quality

我该如何解决？

谢谢

1 个答案:

答案 0 :(得分：0)

您的问题是您编码了不同的表名。该表是使用eqq_table创建的，而查询尝试访问egg_table。

减少此类错误可能性的一种方法是为此类值定义CONSTANT，然后始终通过各自的CONSTANT引用这些项（表名，列名，索引名等）。

因此，我建议更改：-

public class DataHelper extends SQLiteOpenHelper {

    private static final String LOGCAT = null;
    private static final String DATABASE_NAME = "layerfarm-mobile.db";
    private static final int DATABASE_VERSION = 1;

    public static final String locationSQL = "CREATE TABLE IF NOT EXISTS location(id integer primary key, name text, address text, rid integer);";
    public static final String eqq_qualitySQL = "CREATE TABLE IF NOT EXISTS  eqq_quality(id integer primary key, name text);";

    public DataHelper(Context context) {
        super(context, DATABASE_NAME, null, DATABASE_VERSION);
        Log.d(LOGCAT,"Created");
        // TODO Auto-generated constructor stub
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        try {
            //Create table
            db.execSQL(locationSQL);
            db.execSQL(eqq_qualitySQL);

        String InsertlocationSQL = "INSERT INTO location (id, name, address, rid) VALUES " +
                "(1,'Location A','Blitar',1)," +
                "(2,'Location B','Blitar',2)," +
                "(3,'Location C','Blitar',3)," +
                "(4,'Location D','Blitar',4);";
        db.execSQL(InsertlocationSQL);

        String InsertEggQualitySQL = "INSERT INTO egg_quality (id, name) VALUES " +
                "(1,'Quality A'), " +
                "(2,'Quality B'), " +
                "(3,'Quality C'), " +
                "(4,'Cracked');";
        db.execSQL(InsertEggQualitySQL);
        }catch (Exception e){
            e.printStackTrace();
        }
    }


    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {

        // Drop table if existed, all data will be gone!!!
        db.execSQL("DROP TABLE IF EXISTS location;"); 
    db.execSQL("DROP TABLE IF EXISTS eqq_quality;"); onCreate(db);
    }
}

至：-

public class DataHelper extends SQLiteOpenHelper {

    private static final String LOGCAT = null;
    private static final String DATABASE_NAME = "layerfarm-mobile.db";
    private static final int DATABASE_VERSION = 1;

    public static final String TABLE_LOCATION = "location";
    public static final String TABLE_EGGQUALITY = "eqq_quality";

    public static final String COL_LOCATION_ID = "id";
    public static final String COL_LOCATION_NAME = "name";
    public static final String COL_LOCATION_ADDRESS = "address";
    public static final String COL_LOCATION_RID = "rid";

    public static final String COl_EGGQUALITY_ID = "id";
    public static final String COL_EGGQUALITY_NAME = "name";

    private String locationSQL = "CREATE TABLE IF NOT EXISTS " + TABLE_LOCATION + "(" +
            COL_LOCATION_ID + " INTEGER PRIMARY KEY, " +
            COL_LOCATION_NAME + " TEXT, " +
            COL_LOCATION_ADDRESS + " TEXT," +
            COL_LOCATION_RID + " INTEGER" +
            ")";
    private String egg_qualitySQL = "CREATE TABLE IF NOT EXISTS " + TABLE_EGGQUALITY + "(" +
            COl_EGGQUALITY_ID + " INTEGER PRIMARY KEY, " +
            COL_EGGQUALITY_NAME + " TEXT" +
            ")";

    SQLiteDatabase mDB;

    public DataHelper(Context context) {
        super(context, DATABASE_NAME, null, DATABASE_VERSION);
        mDB = this.getWritableDatabase();
        //Log.d(LOGCAT,"Created"); //????? Not correct as the database doesn't get created until an attempt is made to open it
        // TODO Auto-generated constructor stub
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        mDB = db;

        /* USING TRY CATCH MAY CAUSE A GREAT DEAL OF CONFUSION
        try {
            //Create table
            db.execSQL(locationSQL);
            db.execSQL(eqq_qualitySQL);

            String InsertlocationSQL = "INSERT INTO location (id, name, address, rid) VALUES " +
                    "(1,'Location A','Blitar',1)," +
                    "(2,'Location B','Blitar',2)," +
                    "(3,'Location C','Blitar',3)," +
                    "(4,'Location D','Blitar',4);";
            db.execSQL(InsertlocationSQL);

            String InsertEggQualitySQL = "INSERT INTO egg_quality (id, name) VALUES " +
                    "(1,'Quality A'), " +
                    "(2,'Quality B'), " +
                    "(3,'Quality C'), " +
                    "(4,'Cracked');";
            db.execSQL(InsertEggQualitySQL);
        }catch (Exception e){
            e.printStackTrace();
        }
        */
        db.execSQL(locationSQL);
        db.execSQL(egg_qualitySQL);
        insertLocation("Location A","Blitar",1);
        insertLocation("Location B", "Blitar",2);
        insertLocation("Location C","Blitar ",3);
        insertLocation("Location D","Blitar",4);
        insertEggQuality("Quality A");
        insertEggQuality("Quality B");
        insertEggQuality("Quality C");
        insertEggQuality("Quality B");
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {

        // Drop table if existed, all data will be gone!!!
        db.execSQL("DROP TABLE IF EXISTS " + TABLE_LOCATION);
        db.execSQL("DROP TABLE IF EXISTS " + TABLE_EGGQUALITY); 
        onCreate(db);
    }

    /**
     * NOTE as ID column is defined as INTEGER PRIMARY KEY, then SQlite will,
     * if no value is specified when inserting a row,
     * generate a unique value for the id column
     *  (initially 1, then likely 2, then likely 3 ......... )
     */
    public long insertLocation(String name, String address, long rid) {
        ContentValues cv = new ContentValues();
        cv.put(COL_LOCATION_NAME,name);
        cv.put(COL_LOCATION_ADDRESS,address);
        cv.put(COL_LOCATION_RID,rid);
        return mDB.insert(TABLE_LOCATION,null,cv);
    }

    public long insertEggQuality(String name) {
        ContentValues cv = new ContentValues();
        cv.put(COL_EGGQUALITY_NAME,name);
        return mDB.insert(TABLE_EGGQUALITY,null,cv);
    }

    public Cursor getAllLocations() {
        return getAll(TABLE_LOCATION);
    }

    public Cursor getAllEggQuality() {
        return getAll(TABLE_EGGQUALITY);
    }

    public Cursor getAll(String table) {
        return mDB.query(table,null,null,null,null,null,null);
    }
}
  • 包括了其他建议的改进
  • 请注意，如果仅当首次创建数据库时才运行添加或更改表的onCreate方法，则应该删除应用程序的数据，卸载应用程序或增加版本号，然后重新运行应用程序（请注意，所有三种方法会导致数据丢失。）

可以在活动中使用上述内容，如下所示：-

public class MainActivity extends AppCompatActivity {

    DataHelper mDBHlpr;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        mDBHlpr = new DataHelper(this);

        Cursor csr = mDBHlpr.getAllLocations();
        DatabaseUtils.dumpCursor(csr);
        csr = mDBHlpr.getAllEggQuality();
        DatabaseUtils.dumpCursor(csr);
    }
}

dumpCursor的结果类似于：-

12-12 04:32:23.854 1248-1248/so53700541.so53700541updatewithexpression I/System.out: >>>>> Dumping cursor android.database.sqlite.SQLiteCursor@534aac14
12-12 04:32:23.854 1248-1248/so53700541.so53700541updatewithexpression I/System.out: 0 {
12-12 04:32:23.854 1248-1248/so53700541.so53700541updatewithexpression I/System.out:    id=1
12-12 04:32:23.854 1248-1248/so53700541.so53700541updatewithexpression I/System.out:    name=Location A
12-12 04:32:23.854 1248-1248/so53700541.so53700541updatewithexpression I/System.out:    address=Blitar
12-12 04:32:23.854 1248-1248/so53700541.so53700541updatewithexpression I/System.out:    rid=1
12-12 04:32:23.854 1248-1248/so53700541.so53700541updatewithexpression I/System.out: }
12-12 04:32:23.854 1248-1248/so53700541.so53700541updatewithexpression I/System.out: 1 {
12-12 04:32:23.854 1248-1248/so53700541.so53700541updatewithexpression I/System.out:    id=2
12-12 04:32:23.854 1248-1248/so53700541.so53700541updatewithexpression I/System.out:    name=Location B
12-12 04:32:23.854 1248-1248/so53700541.so53700541updatewithexpression I/System.out:    address=Blitar
12-12 04:32:23.854 1248-1248/so53700541.so53700541updatewithexpression I/System.out:    rid=2
12-12 04:32:23.854 1248-1248/so53700541.so53700541updatewithexpression I/System.out: }
12-12 04:32:23.854 1248-1248/so53700541.so53700541updatewithexpression I/System.out: 2 {
12-12 04:32:23.854 1248-1248/so53700541.so53700541updatewithexpression I/System.out:    id=3
12-12 04:32:23.854 1248-1248/so53700541.so53700541updatewithexpression I/System.out:    name=Location C
12-12 04:32:23.854 1248-1248/so53700541.so53700541updatewithexpression I/System.out:    address=Blitar 
12-12 04:32:23.854 1248-1248/so53700541.so53700541updatewithexpression I/System.out:    rid=3
12-12 04:32:23.854 1248-1248/so53700541.so53700541updatewithexpression I/System.out: }
12-12 04:32:23.854 1248-1248/so53700541.so53700541updatewithexpression I/System.out: 3 {
12-12 04:32:23.854 1248-1248/so53700541.so53700541updatewithexpression I/System.out:    id=4
12-12 04:32:23.854 1248-1248/so53700541.so53700541updatewithexpression I/System.out:    name=Location D
12-12 04:32:23.854 1248-1248/so53700541.so53700541updatewithexpression I/System.out:    address=Blitar
12-12 04:32:23.854 1248-1248/so53700541.so53700541updatewithexpression I/System.out:    rid=4
12-12 04:32:23.854 1248-1248/so53700541.so53700541updatewithexpression I/System.out: }
12-12 04:32:23.854 1248-1248/so53700541.so53700541updatewithexpression I/System.out: <<<<<
12-12 04:32:23.854 1248-1248/so53700541.so53700541updatewithexpression I/System.out: >>>>> Dumping cursor android.database.sqlite.SQLiteCursor@534c5e0c
12-12 04:32:23.854 1248-1248/so53700541.so53700541updatewithexpression I/System.out: 0 {
12-12 04:32:23.854 1248-1248/so53700541.so53700541updatewithexpression I/System.out:    id=1
12-12 04:32:23.854 1248-1248/so53700541.so53700541updatewithexpression I/System.out:    name=Quality A
12-12 04:32:23.854 1248-1248/so53700541.so53700541updatewithexpression I/System.out: }
12-12 04:32:23.854 1248-1248/so53700541.so53700541updatewithexpression I/System.out: 1 {
12-12 04:32:23.854 1248-1248/so53700541.so53700541updatewithexpression I/System.out:    id=2
12-12 04:32:23.854 1248-1248/so53700541.so53700541updatewithexpression I/System.out:    name=Quality B
12-12 04:32:23.854 1248-1248/so53700541.so53700541updatewithexpression I/System.out: }
12-12 04:32:23.854 1248-1248/so53700541.so53700541updatewithexpression I/System.out: 2 {
12-12 04:32:23.854 1248-1248/so53700541.so53700541updatewithexpression I/System.out:    id=3
12-12 04:32:23.854 1248-1248/so53700541.so53700541updatewithexpression I/System.out:    name=Quality C
12-12 04:32:23.854 1248-1248/so53700541.so53700541updatewithexpression I/System.out: }
12-12 04:32:23.854 1248-1248/so53700541.so53700541updatewithexpression I/System.out: 3 {
12-12 04:32:23.854 1248-1248/so53700541.so53700541updatewithexpression I/System.out:    id=4
12-12 04:32:23.854 1248-1248/so53700541.so53700541updatewithexpression I/System.out:    name=Quality B
12-12 04:32:23.854 1248-1248/so53700541.so53700541updatewithexpression I/System.out: }
12-12 04:32:23.854 1248-1248/so53700541.so53700541updatewithexpression I/System.out: <<<<<
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