Question

无法想出这个。我正在升级数据库，我创建了一个函数来重命名列，方法是将原始表重命名为临时表，然后使用重命名的字段创建一个新表，然后将所有数据从临时表复制到新表，但它失败了在进入复制数据时。

执行重命名的功能：

public void modifyColumn(SQLiteDatabase db, String oldColumnName, String newColumnName, String[] newColumnConstraints) {

    // get current table columns
    String sql = String.format("PRAGMA table_info('%s')", TABLE_NAME);
    Cursor cursor = db.rawQuery(sql, new String[] {});

    int length = cursor.getCount();
    String[] oC = new String[length], nC = new String[length], c = new String[length];

    while(cursor.moveToNext()){
        int cid = cursor.getInt(cursor.getColumnIndex("cid"));
        String name = cursor.getString(cursor.getColumnIndex("name"));
        String type = cursor.getString(cursor.getColumnIndex("type"));
        int notnull = cursor.getInt(cursor.getColumnIndex("notnull"));
        String dflt = cursor.getString(cursor.getColumnIndex("dflt_value"));
        int pk = cursor.getInt(cursor.getColumnIndex("pk"));

        Vector<String> constraints = new Vector<String>();

        // add data type to field
        constraints.add(type);

        // add primary key option to field
        if(pk > 0)
            constraints.add("PRIMARY KEY");

        // add not null option to field
        if(notnull > 0)
            constraints.add("NOT NULL");

        // add default value to field
        if(dflt != null)
            constraints.add("DEFAULT " + dflt);

        String cName = name;
        String cType = TextUtils.join(" ", constraints.toArray());

        oC[cid] = cName;
        cName = (cName.equals(oldColumnName))? newColumnName : cName;
        nC[cid] = cName;

        if(newColumnConstraints != null)
            cType = TextUtils.join(" ", newColumnConstraints);

        c[cid] = cName + " " + cType;
    }


    // rename old table
    this.renameTable(db, "tmp_" + TABLE_NAME);

    // create new table with modified column
    this.createTable(db, TABLE_NAME, c);

    // copy data from temporary table to new table
    sql = "INSERT INTO " + TABLE_NAME + " (" + TextUtils.join(", ", nC) + 
            ") SELECT (" + TextUtils.join(", ", oC) + ") FROM tmp_" + TABLE_NAME;
    db.execSQL(sql);

    // drop temporary table
    db.execSQL("DROP TABLE tmp_" + TABLE_NAME);
}

在“将数据从临时表复制到新表”注释中，执行之前的sql如下所示：

INSERT INTO vehicles (_id, vLabel, vYear, vMake, vModel, vOption, vDetail, vAdded) SELECT (id, vLabel, vYear, vMake, vModel, vOption, vDetail, vAdded) FROM tmp_vehicles

然后我得到以下错误输出：

06-08 19:33:05.888: E/Database(21562): Failure 1 (near ",": syntax error) on 0x2037d8 when preparing 'INSERT INTO vehicles (_id, vLabel, vYear, vMake, vModel, vOption, vDetail, vAdded) SELECT (id, vLabel, vYear, vMake, vModel, vOption, vDetail, vAdded) FROM tmp_vehicles'.
06-08 19:33:08.711: W/dalvikvm(21562): threadid=1: thread exiting with uncaught exception (group=0x4001f560)
06-08 19:33:08.771: E/AndroidRuntime(21562): FATAL EXCEPTION: main
06-08 19:33:08.771: E/AndroidRuntime(21562): java.lang.RuntimeException: Unable to start activity 
06-08 19:33:08.771: E/AndroidRuntime(21562):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1648)
06-08 19:33:08.771: E/AndroidRuntime(21562):    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1662)
06-08 19:33:08.771: E/AndroidRuntime(21562):    at android.app.ActivityThread.access$1500(ActivityThread.java:117)
06-08 19:33:08.771: E/AndroidRuntime(21562):    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:931)
06-08 19:33:08.771: E/AndroidRuntime(21562):    at android.os.Handler.dispatchMessage(Handler.java:99)
06-08 19:33:08.771: E/AndroidRuntime(21562):    at android.os.Looper.loop(Looper.java:130)
06-08 19:33:08.771: E/AndroidRuntime(21562):    at android.app.ActivityThread.main(ActivityThread.java:3696)
06-08 19:33:08.771: E/AndroidRuntime(21562):    at java.lang.reflect.Method.invokeNative(Native Method)
06-08 19:33:08.771: E/AndroidRuntime(21562):    at java.lang.reflect.Method.invoke(Method.java:507)
06-08 19:33:08.771: E/AndroidRuntime(21562):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:866)
06-08 19:33:08.771: E/AndroidRuntime(21562):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:624)
06-08 19:33:08.771: E/AndroidRuntime(21562):    at dalvik.system.NativeStart.main(Native Method)

Answer 1

选择语法错误。

替换

SELECT (column1, column2, ...)

与

SELECT column1, column2, ...

即。删除括号。

引起：android.database.sqlite.SQLiteException：无法从版本升级只读数据库

1 个答案: