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我正在尝试通过组合其他三个整数字段来更新我的 SQLite 数据库中的整数字段，但如果字段值的长度为 1，我还需要在其他字段中的两个前面加上零。

这是我试图通过 DBAdapter 类中的升级数据库方法执行的例程。

所以我需要改变这个当前的更新：

if (newVersion==2) {
  populatesql = "update " + DB_TABLE + 
                " set field1="+ COL_FIELD2 +
                " || " +
                COL_FIELD3 + 
                " || " + 
                COL_FIELD4;
}

像这样的东西（是的，我知道前缀零不起作用，因为它需要字符串而不是整数，但我用字符串尝试了它并使其成为静态但它不起作用）

if (newVersion==2) {
  populatesql = "update " + DB_TABLE + 
                " set field1="+ COL_FIELD2 +
                " || " +
                prefixzero(COL_FIELD3) + 
                " || " + 
                prefixzero(COL_FIELD4);
}

public String prefixzero(String number) {
    String result = Integer.toString(number);

    // Log.d("PREFIX", "result starts with this = "+result);
    if (result.length() >1 ) {
      // Log.d("PREFIX", "NO ZEROES HERE");
      return Integer.toString(number);
    }

   String zeroprefix = "";
   zeroprefix = "0"+result;
   // Log.d("PREFIX", zeroprefix);

   return zeroprefix ;
}

数据库字段声明如下：

public static final String COL_FIELD4 = "day";
public static final String COL_FIELD3 = "month";
public static final String COL_FIELD2 = "year";
public static final String COL_FIELD1 = "long_date";

这是我忽略空格的错误。就像没有空格的想法一样，字段名称只是简单地连接在一起。使用的代码低于此错误。

02-28 07:34:00.919: E/AndroidRuntime(18332): java.lang.RuntimeException: Unable to start activity ComponentInfo{co.uk.common.myapp/co.uk.common.myapp.MainActivity}: android.database.sqlite.SQLiteException: no such column: yearmonthday: update Log set long_date= yearmonthday
02-28 07:34:00.919: E/AndroidRuntime(18332):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1658)
02-28 07:34:00.919: E/AndroidRuntime(18332):    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1674)
02-28 07:34:00.919: E/AndroidRuntime(18332):    at android.app.ActivityThread.access$1500(ActivityThread.java:117)
02-28 07:34:00.919: E/AndroidRuntime(18332):    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:942)
02-28 07:34:00.919: E/AndroidRuntime(18332):    at android.os.Handler.dispatchMessage(Handler.java:99)
02-28 07:34:00.919: E/AndroidRuntime(18332):    at android.os.Looper.loop(Looper.java:130)
02-28 07:34:00.919: E/AndroidRuntime(18332):    at android.app.ActivityThread.main(ActivityThread.java:3735)
02-28 07:34:00.919: E/AndroidRuntime(18332):    at java.lang.reflect.Method.invokeNative(Native Method)
02-28 07:34:00.919: E/AndroidRuntime(18332):    at java.lang.reflect.Method.invoke(Method.java:507)
02-28 07:34:00.919: E/AndroidRuntime(18332):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:904)
02-28 07:34:00.919: E/AndroidRuntime(18332):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:662)
02-28 07:34:00.919: E/AndroidRuntime(18332):    at dalvik.system.NativeStart.main(Native Method)
02-28 07:34:00.919: E/AndroidRuntime(18332): Caused by: android.database.sqlite.SQLiteException: no such column: yearmonthday: update Log set long_date= yearmonthday
02-28 07:34:00.919: E/AndroidRuntime(18332):    at android.database.sqlite.SQLiteDatabase.native_execSQL(Native Method)
02-28 07:34:00.919: E/AndroidRuntime(18332):    at android.database.sqlite.SQLiteDatabase.execSQL(SQLiteDatabase.java:1763)
02-28 07:34:00.919: E/AndroidRuntime(18332):    at co.uk.shieldstothemax.blastedneighbours.DBAdapter$DBHelper.onUpgrade(DBAdapter.java:68)
02-28 07:34:00.919: E/AndroidRuntime(18332):    at android.database.sqlite.SQLiteOpenHelper.getWritableDatabase(SQLiteOpenHelper.java:132)
02-28 07:34:00.919: E/AndroidRuntime(18332):    at co.uk.shieldstothemax.blastedneighbours.DBAdapter.open(DBAdapter.java:87)
02-28 07:34:00.919: E/AndroidRuntime(18332):    at co.uk.shieldstothemax.blastedneighbours.MainActivity.onCreate(MainActivity.java:123)
02-28 07:34:00.919: E/AndroidRuntime(18332):    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
02-28 07:34:00.919: E/AndroidRuntime(18332):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1622)

onUpgrade 方法中的代码：

if (newVersion==2) {

                 populatesql = "update "+ DB_TABLE +" set long_date= "+getDateStr(COL_FIELD2,COL_FIELD3,COL_FIELD4);                
                }

getDateStr：

public static String getDateStr(String year, String month,String day) {
        return year+ prefixfieldzero(month)+ prefixfieldzero(day);
     }

前缀字段零：

public static String prefixfieldzero(String number) {
            String result = String.valueOf(number);
          //  Log.d("PREFIX", "result starts with this = "+result);
            if (result.length() >1 ) {
             // Log.d("PREFIX", "NO ZEROES HERE");
             return number;
             }

           String zerofieldprefix = "";
           zerofieldprefix = "0"+result;
          // Log.d("PREFIX", zeroprefix);

              return zerofieldprefix ;
        }

这是我的 DBAdapter ：

import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.util.Log;


public class DBAdapter {
    private static final String DB_NAME = "TABLE";
    private static final String DB_TABLE = "Log";
    private static final int DB_VERSION = 2;

    private static final String DB_CREATE = "CREATE TABLE IF NOT EXISTS "+DB_TABLE+ 
                " (_id INTEGER PRIMARY KEY AUTOINCREMENT, " + 
                       "type_id INTEGER, " +" hour INTEGER, " + 
                         "min INTEGER , " +" info VARCHAR,"+"image_desc VARCHAR, "+ 
                       "day INTEGER, "+"month INTEGER,  "+ "year INTEGER,"+" second INTEGER,long_date INTEGER ,date_time_long INTEGER NOT NULL "+");" ;


        public static final String COL_TYPE = "type_id";
        public static final String COL_HOUR = "hour";
        public static final String COL_MIN = "min";
        public static final String COL_SEC = "second";
        public static final String COL_IMAGE = "image_desc";

        public static final String COL_DAY = "day";
        public static final String COL_MON = "month";
        public static final String COL_YEAR = "year";
        public static final String COL_DATE = "date";
        public static final String COL_LONG_DATE = "long_date";
        public static final String COL_INFO = "info";   
        public static final String COL_ID = "_id";

        private SQLiteDatabase mDB;
        private DBHelper mDBHelper;
        private Context mCtx;

        private static class DBHelper extends SQLiteOpenHelper{
            public DBHelper(Context context) {
                super(context, DB_NAME, null, DB_VERSION);
            }

            @Override
            public void onCreate(SQLiteDatabase db) {
                db.execSQL(DB_CREATE);

            }

            @Override
            public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
                Log.v("OLDDBVERSION", "Old version="+String.valueOf(oldVersion));
                Log.v("NEWDBVERSION", "New version="+String.valueOf(newVersion));
                //String upgradesql = null;
                String populatesql = null;
                if (newVersion==2) {

                 populatesql = "update "+ DB_TABLE +" set long_date= "+getDateStr(COL_YEAR,COL_MON,COL_DAY);                
                }
                if (populatesql !=null) {
                    //db.execSQL(upgradesql);               
                    if (populatesql !=null) {

                        db.execSQL(populatesql);
                    }
                }



        } 
   }

        public DBAdapter(Context ctx)
        {
            this.mCtx = ctx;
        }

        //OPEN METHOD AND CLOSE METHOD
        public DBAdapter open()
        {
            mDBHelper = new DBHelper(mCtx);
            mDB = mDBHelper.getWritableDatabase(); //important
            return this;
        }

        public void close()
        {
            mDBHelper.close();
        }

        //INSERT AND DELETE
        public long createLog(String info,String image, Integer type,Integer hour,Integer mins,Integer sec,Integer day,Integer month,Integer year,Long longdate,Long date)
        {
            ContentValues v = new ContentValues();
            v.put(COL_TYPE, type);
            v.put(COL_INFO, info);
            v.put(COL_IMAGE, image);
            v.put(COL_HOUR, hour);
            v.put(COL_SEC, sec);
            v.put(COL_MIN, mins);
            v.put(COL_DAY, day);
            v.put(COL_MON, month);
            v.put(COL_YEAR, year);
            v.put(COL_DATE, date);
            v.put(COL_LONG_DATE, longdate);

            return mDB.insert(DB_TABLE, null, v);
        }

        public boolean deleteLogRec(long id)
        {
            return mDB.delete(DB_TABLE, COL_ID + "="+ id, null)>0;
        }

        public boolean deleteAllLogs()
        {
            return mDB.delete(DB_TABLE, null, null)>0;
        }

        //get all bookmark
        public Cursor GetAllLogs(Integer i,String sortfield)
        {
            String sorted = "";
            if (i == 1 ) {
                sorted = "DESC";
            } else if (i == 2) {
                sorted = "ASC";
            } 


            return mDB.query(DB_TABLE, new String[] {COL_ID, COL_TYPE,COL_IMAGE, COL_INFO,COL_IMAGE,COL_HOUR,COL_SEC,COL_MIN,COL_DAY,COL_MON,COL_YEAR,COL_SORT_DATE},
                            null, null, null, null, COL_DATE+" "+sorted);
        }

        public Cursor allrecords() {

            return mDB.query(DB_TABLE, new String[] {COL_ID, COL_TYPE,COL_IMAGE, COL_INFO,COL_IMAGE,COL_HOUR,COL_SEC,COL_MIN,COL_DAY,COL_MON,COL_YEAR,COL_SORT_DATE},
                    null, null, null, null, null);
        }





        //get a specific log by id
        public Cursor getLog(long id)
        {
            Cursor mCursor = mDB.query(true, DB_TABLE, new String[] {COL_ID, COL_TYPE,COL_IMAGE, COL_INFO,COL_IMAGE,COL_HOUR,COL_SEC,COL_MIN,COL_DAY,COL_MON,COL_YEAR},
                    COL_ID + "=" + id,
                    null, null, null, null, null);

            if (mCursor!=null)
                mCursor.moveToFirst();
            return mCursor;
        }

        //finally update the log
        public boolean updateLog(long id, String uinfo, String uimage,Integer utype,Integer uhour,Integer usec,Integer umin,Integer uday,Integer umonth,Integer uyear,Long ulongdate,Long udate)
        {
            ContentValues v = new ContentValues();
            v.put(COL_TYPE, utype);
            v.put(COL_INFO, uinfo);
            v.put(COL_IMAGE, uimage);
            v.put(COL_HOUR, uhour);
            v.put(COL_SEC, usec);
            v.put(COL_MIN, umin);
            v.put(COL_DAY, uday);
            v.put(COL_MON, umonth);
            v.put(COL_YEAR, uyear);
            v.put(COL_DATE, udate);
            v.put(COL_SORT_DATE, ulongdate);

            return mDB.update(DB_TABLE, v, COL_ID + "=" + id, null) > 0;
        }   

        public static String prefixfieldzero(String number) {
            String result = String.valueOf(number);
          //  Log.d("PREFIX", "result starts with this = "+result);
            if (result.length() >1 ) {
             // Log.d("PREFIX", "NO ZEROES HERE");
             return number;
             }

           String zerofieldprefix = "";
           zerofieldprefix = "0"+result;
          // Log.d("PREFIX", zeroprefix);

              return zerofieldprefix ;
        }

    public static String getDateStr(String year, String month,String day) {
            return year+ prefixfieldzero(month)+ prefixfieldzero(day);
         }


}

尝试根据您的最新答案运行 SQL，但收到此错误：

03-01 00:20:05.379: E/AndroidRuntime(19060): Caused by: android.database.sqlite.SQLiteException: near "AS": syntax error: update TABLE AS TABLE_Temp1 set long_date = (select year || substr('00' || month ,-2,2  ) || substr('00' || ,day, -2 ,2)  from Log AS TABLE_Temp2 where TABLE_Temp1.id=TABLE_Temp2.id

当前 SQL 用于将长日期更新为年月日的组合：

populatesql = "update "+DB_TABLE + " AS LogTemp1 set long_date = (select year || substr('00' || month ,-2,2  ) || substr('00' || ,day, -2 ,2)  from "+DB_TABLE+" AS LogTemp2 where LogTemp1.id=LogTemp2.id   "  ;

我也试过如下：

populatesql = "update "+DB_TABLE + " AS LogTemp1 set long_date = (select year || substr('00' || month ,-2,2  ) || substr('00' || ,day, -2 ,2)  from "+DB_TABLE+" AS LogTemp2 where **LogTemp1._id=LogTemp2._id**   "  ;
4

2 回答 2

1

好吧，我终于得到了，你想要什么。您需要一个更新语句，根据其当前值更新每一行。当然，您不能从 SQLite 数据库调用 Java 代码中的函数。因此，一切都必须在 SQLite 本身的 UPDATE 语句中完成。

鉴于此，您的陈述应如下所示：

UPDATE yourTable AS table1 
SET date = 
    (SELECT year || 
            substr('00' || month, -2, 2) || 
            substr('00' || day, -2, 2) 
     FROM yourTable AS table2 
     WHERE table1.id = table2.id);

您只需将我在此处使用的名称替换为您实际使用的名称，并为其创建一个有效的 Java 字符串。

这些substr('00' || month, -2, 2)语句执行lpad其他数据库引擎的语句（在 SQLite 中不可用）将执行的操作。

你可以这样读：用一个数字连接两个零，然后取结果字符串最右边的两个字符。-2均值，从右边缘开始计算子串，均值2将两个字符作为结果子串。

此lpad替换基于Jason Hinkle的博文。

于 2013-02-28T20:49:33.547 回答
0

假设 COL_FIELD2... 是字符串值，为什么不这样做呢？

     if (newVersion==2) {
       populatesql = "update " + DB_TABLE + 
                     " set field1 = " + getDateStr(COL_FIELD2, COL_FIELD3, COL_FIELD4);
     }

     getDateStr(String year, String month,String day) {
        return year + prefixzero(month) + prefixzero(day);
     }

     public String prefixzero(String number) {
        //Log.d("PREFIX", "result starts with this = "+result);
        if (number.length() > 1) {
           //Log.d("PREFIX", "NO ZEROES HERE");
           return number;
        }            
        number = "0" + number;
        //Log.d("PREFIX", zeroprefix);            
        return zeroprefix ;
     }

如果它们是int-values，您可以改用以下prefixzero()方法（当然也可以调整方法签名getDateStr()：

     public String prefixzero(int number) {
        if (number > 9) {
           return Integer.toString(number);
        }
        return "0" + number;
     }
于 2013-02-27T21:07:40.013 回答