我想用光标来查看一个TextView数据库的内容,但是当我尝试运行应用程序崩溃......我不能确定它的误差
包aditya.testapp;
进口android.content.ContentValues;
进口android.content.Context;
进口android.database.Cursor;
进口android.database.SQLException;
进口android.database.sqlite.SQLiteDatabase;
进口android.database.sqlite.SQLiteOpenHelper;
公共类SQLDATA {
公共静态最后弦乐KEY_ROWID =_id;
公共静态最后弦乐KEY_NAME =persons_name;
公共静态最后弦乐KEY_NUMBER =persons_number;
私有静态最后弦乐DATABASE_NAME =DataDb;
私有静态最后弦乐DATABASE_TABLE =peopleTable;
私有静态最终诠释DATABASE_VERSION = 2;
私人DbHelper ourHelper;
私人最终语境ourContext;
私人SQLiteDatabase ourDatabase;
//XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
私有静态类DbHelper扩展SQLiteOpenHelper {
公共DbHelper(上下文的背景下){
超(背景下,DATABASE_NAME,空,DATABASE_VERSION);
// TODO自动生成构造函数存根
}
// onCreate方法仅在创建数据库时,使用一次....其他时间onUpgrade梅索德使用
@覆盖
公共无效的onCreate(SQLiteDatabase DB){
// TODO自动生成方法存根
db.execSQL(CREATE TABLE+ DATABASE_TABLE +(+
KEY_ROWID +INTEGER PRIMARY KEY,+
KEY_NAME +TEXT NOT NULL,+
KEY_NUMBER +TEXT NOT NULL);
);
}
@覆盖
公共无效onUpgrade(SQLiteDatabase分贝,INT oldVersion,诠释静态网页){
// TODO自动生成方法存根
db.execSQL(DROP TABLE IF EXISTS+ DATABASE_TABLE);
的onCreate(DB);
}}
//初始化背景下ourContext
公共SQLDATA(上下文C){
ourContext = C;
}
// XX
公共SQLDATA的open()抛出的SQLException {
ourHelper =新DbHelper(ourContext);
ourDatabase = ourHelper.getWritableDatabase();
回到这一点;
}
公共无效的close(){
ourHelper.close();
}
众长createEntry(字符串名称,串号){
// TODO自动生成方法存根
//表ContentValues用来束代替
ContentValues CV =新ContentValues();
cv.put(KEY_NAME,姓名);
cv.put(KEY_NUMBER,数量);
返回ourDatabase.insert(DATABASE_TABLE,空,CV);
}
公共字符串的getData(){
// TODO自动生成方法存根
的String []列=新的String [] {KEY_ROWID,KEY_NAME,KEY_NUMBER};
光标C = ourDatabase.query(DATABASE_TABLE,列,NULL,NULL,NULL,NULL,NULL);
字符串结果=;
INT iRow = c.getColumnIndex(KEY_ROWID);
INT INAME = c.getColumnIndex(KEY_NAME);
INT i编号= c.getColumnIndex(KEY_NUMBER);
为(c.moveToFirst();!c.isAfterLast(); c.moveToNext()){
结果=结果+ c.getString(iRow)++ c.getString(INAME)++ c.getString(i编号)+/ N的;
}
c.close();
返回结果;
}
}
和此code是对于被用于查看数据库中的类
进口android.app.Activity;
进口android.os.Bundle;
进口android.widget.TextView;
公共类SqlView延伸活动{
@覆盖
保护无效的onCreate(包savedInstanceState){
// TODO自动生成方法存根
super.onCreate(savedInstanceState);
的setContentView(R.layout.sqlview);
TextView的lblSqlInfo =(TextView中)findViewById(R.id.lblSqlInfo);
SQLDATA信息=新SQLDATA(本);
info.open();
字符串数据= info.getData(); //的getData是SQLDATA类中的方法
info.close();
lblSqlInfo.setText(数据);
}
}
请帮忙找出错误....日志猫显示此错误
12月10日至22日:51:56.483:E / AndroidRuntime(1815):致命异常:主要
12月10号至22日:51:56.483:E / AndroidRuntime(1815):java.lang.RuntimeException的:无法启动的活动ComponentInfo {aditya.testapp / aditya.testapp.SqlView}:android.database.sqlite.SQLiteException:没有这样的列:_id(code 1):在编制:选择_id,persons_name,persons_number从peopleTable
12月10号至22日:51:56.483:E / AndroidRuntime(1815):在android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2230)
12月10号至22日:51:56.483:E / AndroidRuntime(1815):在android.app.ActivityThread.access $ 600(ActivityThread.java:141)
12月10号至22日:51:56.483:E / AndroidRuntime(1815):在android.app.ActivityThread $ H.handleMessage(ActivityThread.java:1234)
12月10号至22日:51:56.483:E / AndroidRuntime(1815):在android.os.Handler.dispatchMessage(Handler.java:99)
12月10号至22日:51:56.483:E / AndroidRuntime(1815):在android.os.Looper.loop(Looper.java:137)
12月10号至22日:51:56.483:E / AndroidRuntime(1815):在android.app.ActivityThread.main(ActivityThread.java:5041)
12月10号至22日:51:56.483:E / AndroidRuntime(1815):在java.lang.reflect.Method.invokeNative(本机方法)
12月10号至22日:51:56.483:E / AndroidRuntime(1815):在java.lang.reflect.Method.invoke(Method.java:511)
12月10号至22日:51:56.483:E / AndroidRuntime(1815):在com.android.internal.os.ZygoteInit $ MethodAndArgsCaller.run(ZygoteInit.java:793)
12月10号至22日:51:56.483:E / AndroidRuntime(1815):在com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
12月10号至22日:51:56.483:E / AndroidRuntime(1815):在dalvik.system.NativeStart.main(本机方法)
12月10号至22日:51:56.483:E / AndroidRuntime(1815):android.database.sqlite.SQLiteException:没有这样的列:_id(code1):由引起的,而编译:选择_id,persons_name,persons_number从peopleTable
12月10号至22日:51:56.483:E / AndroidRuntime(1815):在android.database.sqlite.SQLiteConnection.native prepareStatement(本机方法)
12月10号至22日:51:56.483:E / AndroidRuntime(1815):在android.database.sqlite.SQLiteConnection.acquire preparedStatement(SQLiteConnection.java:882)
12月10号至22日:51:56.483:E / AndroidRuntime(1815):在android.database.sqlite.SQLiteConnection prepare(SQLiteConnection.java:493)
12月10号至22日:51:56.483:E / AndroidRuntime(1815):在android.database.sqlite.SQLiteSession prepare(SQLiteSession.java:588)
12月10号至22日:51:56.483:E / AndroidRuntime(1815):在android.database.sqlite.SQLiteProgram< INIT>(SQLiteProgram.java:58)
12月10号至22日:51:56.483:E / AndroidRuntime(1815):在android.database.sqlite.SQLiteQuery< INIT>(SQLiteQuery.java:37)
12月10号至22日:51:56.483:E / AndroidRuntime(1815):在android.database.sqlite.SQLiteDirectCursorDriver.query(SQLiteDirectCursorDriver.java:44)
12月10号至22日:51:56.483:E / AndroidRuntime(1815):在android.database.sqlite.SQLiteDatabase.rawQueryWithFactory(SQLiteDatabase.java:1314)
12月10号至22日:51:56.483:E / AndroidRuntime(1815):在android.database.sqlite.SQLiteDatabase.queryWithFactory(SQLiteDatabase.java:1161)
12月10号至22日:51:56.483:E / AndroidRuntime(1815):在android.database.sqlite.SQLiteDatabase.query(SQLiteDatabase.java:1032)
12月10号至22日:51:56.483:E / AndroidRuntime(1815):在android.database.sqlite.SQLiteDatabase.query(SQLiteDatabase.java:1200)
12月10号至22日:51:56.483:E / AndroidRuntime(1815):在aditya.testapp.SqlData.getData(SqlData.java:79)
12月10号至22日:51:56.483:E / AndroidRuntime(1815):在aditya.testapp.SqlView.onCreate(SqlView.java:16)
12月10号至22日:51:56.483:E / AndroidRuntime(1815):在android.app.Activity.performCreate(Activity.java:5104)
12月10号至22日:51:56.483:E / AndroidRuntime(1815):在android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1080)
12月10号至22日:51:56.483:E / AndroidRuntime(1815):在android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2144)
12月10号至22日:51:56.483:E / AndroidRuntime(1815):11 ...更多
解决方案
android.database.sqlite.SQLiteException:没有这样的列:_id(code 1):在编制:选择_id,persons_name,persons_number从peopleTable
您的表没有一个名为 _id
列。添加它,并重新创建数据库。或者从您的选择列中删除。
好像有在的onCreate SQL语法问题()
:
db.execSQL(CREATE TABLE+ DATABASE_TABLE +(+
KEY_ROWID +INTEGER PRIMARY KEY,+
KEY_NAME +TEXT NOT NULL,+
KEY_NUMBER +TEXT NOT NULL);
应该有列名和类型,如:
之间的空间 db.execSQL(CREATE TABLE+ DATABASE_TABLE +(+
KEY_ROWID +INTEGER PRIMARY KEY,+
KEY_NAME +TEXT NOT NULL,+
KEY_NUMBER +TEXT NOT NULL);
这是因为例如一个棘手的问题 _idINTEGER PRIMARY KEY
是一个有效的列规范,它只是不指定指定的列 _id
。
在改变这样的模式,记得撞了数据库的版本号。
I am trying to view the contents of a database in a TextView by using Cursor but when i try running the app crashes...I cannot identify it the error
package aditya.testapp;
import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.SQLException;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
public class SqlData {
public static final String KEY_ROWID = "_id";
public static final String KEY_NAME = "persons_name";
public static final String KEY_NUMBER = "persons_number";
private static final String DATABASE_NAME = "DataDb";
private static final String DATABASE_TABLE = "peopleTable";
private static final int DATABASE_VERSION = 2 ;
private DbHelper ourHelper;
private final Context ourContext;
private SQLiteDatabase ourDatabase;
//XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
private static class DbHelper extends SQLiteOpenHelper{
public DbHelper(Context context) {
super(context, DATABASE_NAME, null, DATABASE_VERSION);
// TODO Auto-generated constructor stub
}
// onCreate method only used once when a database is created....other times onUpgrade methode is used
@Override
public void onCreate(SQLiteDatabase db) {
// TODO Auto-generated method stub
db.execSQL("CREATE TABLE " + DATABASE_TABLE + " (" +
KEY_ROWID + "INTEGER PRIMARY KEY, " +
KEY_NAME + "TEXT NOT NULL, " +
KEY_NUMBER + "TEXT NOT NULL);"
);
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
// TODO Auto-generated method stub
db.execSQL("DROP TABLE IF EXISTS " + DATABASE_TABLE);
onCreate(db);
}}
// initializing context ourContext
public SqlData (Context c){
ourContext = c;
}
//XX
public SqlData open() throws SQLException{
ourHelper = new DbHelper(ourContext);
ourDatabase = ourHelper.getWritableDatabase();
return this;
}
public void close(){
ourHelper.close();
}
public long createEntry(String name, String number) {
// TODO Auto-generated method stub
// in table ContentValues is used instead of bundle
ContentValues cv = new ContentValues();
cv.put(KEY_NAME, name);
cv.put(KEY_NUMBER, number);
return ourDatabase.insert(DATABASE_TABLE, null, cv);
}
public String getData() {
// TODO Auto-generated method stub
String[] columns = new String[]{KEY_ROWID , KEY_NAME , KEY_NUMBER};
Cursor c = ourDatabase.query(DATABASE_TABLE, columns, null, null, null, null, null);
String result = "";
int iRow = c.getColumnIndex(KEY_ROWID);
int iName = c.getColumnIndex(KEY_NAME);
int iNumber = c.getColumnIndex(KEY_NUMBER);
for( c.moveToFirst(); !c.isAfterLast(); c.moveToNext()){
result = result + c.getString(iRow) + " " + c.getString(iName) + " " + c.getString(iNumber) + "/n";
}
c.close();
return result;
}
}
and this code is for the class which is used to view the database
import android.app.Activity;
import android.os.Bundle;
import android.widget.TextView;
public class SqlView extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
setContentView(R.layout.sqlview);
TextView lblSqlInfo = (TextView) findViewById(R.id.lblSqlInfo);
SqlData info = new SqlData(this);
info.open();
String data = info.getData(); // getData is a method in SqlData class
info.close();
lblSqlInfo.setText(data);
}
}
Please help to find out the error.... The log cat shows this error
10-22 12:51:56.483: E/AndroidRuntime(1815): FATAL EXCEPTION: main
10-22 12:51:56.483: E/AndroidRuntime(1815): java.lang.RuntimeException: Unable to start activity ComponentInfo{aditya.testapp/aditya.testapp.SqlView}: android.database.sqlite.SQLiteException: no such column: _id (code 1): , while compiling: SELECT _id, persons_name, persons_number FROM peopleTable
10-22 12:51:56.483: E/AndroidRuntime(1815): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2230)
10-22 12:51:56.483: E/AndroidRuntime(1815): at android.app.ActivityThread.access$600(ActivityThread.java:141)
10-22 12:51:56.483: E/AndroidRuntime(1815): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1234)
10-22 12:51:56.483: E/AndroidRuntime(1815): at android.os.Handler.dispatchMessage(Handler.java:99)
10-22 12:51:56.483: E/AndroidRuntime(1815): at android.os.Looper.loop(Looper.java:137)
10-22 12:51:56.483: E/AndroidRuntime(1815): at android.app.ActivityThread.main(ActivityThread.java:5041)
10-22 12:51:56.483: E/AndroidRuntime(1815): at java.lang.reflect.Method.invokeNative(Native Method)
10-22 12:51:56.483: E/AndroidRuntime(1815): at java.lang.reflect.Method.invoke(Method.java:511)
10-22 12:51:56.483: E/AndroidRuntime(1815): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
10-22 12:51:56.483: E/AndroidRuntime(1815): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
10-22 12:51:56.483: E/AndroidRuntime(1815): at dalvik.system.NativeStart.main(Native Method)
10-22 12:51:56.483: E/AndroidRuntime(1815): Caused by: android.database.sqlite.SQLiteException: no such column: _id (code 1): , while compiling: SELECT _id, persons_name, persons_number FROM peopleTable
10-22 12:51:56.483: E/AndroidRuntime(1815): at android.database.sqlite.SQLiteConnection.nativePrepareStatement(Native Method)
10-22 12:51:56.483: E/AndroidRuntime(1815): at android.database.sqlite.SQLiteConnection.acquirePreparedStatement(SQLiteConnection.java:882)
10-22 12:51:56.483: E/AndroidRuntime(1815): at android.database.sqlite.SQLiteConnection.prepare(SQLiteConnection.java:493)
10-22 12:51:56.483: E/AndroidRuntime(1815): at android.database.sqlite.SQLiteSession.prepare(SQLiteSession.java:588)
10-22 12:51:56.483: E/AndroidRuntime(1815): at android.database.sqlite.SQLiteProgram.<init>(SQLiteProgram.java:58)
10-22 12:51:56.483: E/AndroidRuntime(1815): at android.database.sqlite.SQLiteQuery.<init>(SQLiteQuery.java:37)
10-22 12:51:56.483: E/AndroidRuntime(1815): at android.database.sqlite.SQLiteDirectCursorDriver.query(SQLiteDirectCursorDriver.java:44)
10-22 12:51:56.483: E/AndroidRuntime(1815): at android.database.sqlite.SQLiteDatabase.rawQueryWithFactory(SQLiteDatabase.java:1314)
10-22 12:51:56.483: E/AndroidRuntime(1815): at android.database.sqlite.SQLiteDatabase.queryWithFactory(SQLiteDatabase.java:1161)
10-22 12:51:56.483: E/AndroidRuntime(1815): at android.database.sqlite.SQLiteDatabase.query(SQLiteDatabase.java:1032)
10-22 12:51:56.483: E/AndroidRuntime(1815): at android.database.sqlite.SQLiteDatabase.query(SQLiteDatabase.java:1200)
10-22 12:51:56.483: E/AndroidRuntime(1815): at aditya.testapp.SqlData.getData(SqlData.java:79)
10-22 12:51:56.483: E/AndroidRuntime(1815): at aditya.testapp.SqlView.onCreate(SqlView.java:16)
10-22 12:51:56.483: E/AndroidRuntime(1815): at android.app.Activity.performCreate(Activity.java:5104)
10-22 12:51:56.483: E/AndroidRuntime(1815): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1080)
10-22 12:51:56.483: E/AndroidRuntime(1815): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2144)
10-22 12:51:56.483: E/AndroidRuntime(1815): ... 11 more
解决方案
android.database.sqlite.SQLiteException: no such column: _id (code 1): , while compiling: SELECT _id, persons_name, persons_number FROM peopleTable
Your table doesn't have a column called _id
. Add it there and recreate the database. Or remove it from your selection columns.
Seems like there are SQL syntax problems in onCreate()
:
db.execSQL("CREATE TABLE " + DATABASE_TABLE + " (" +
KEY_ROWID + "INTEGER PRIMARY KEY, " +
KEY_NAME + "TEXT NOT NULL, " +
KEY_NUMBER + "TEXT NOT NULL);"
There should be space between column name and type, e.g.
db.execSQL("CREATE TABLE " + DATABASE_TABLE + " (" +
KEY_ROWID + " INTEGER PRIMARY KEY, " +
KEY_NAME + " TEXT NOT NULL, " +
KEY_NUMBER + " TEXT NOT NULL);"
This is a tricky issue since e.g. _idINTEGER PRIMARY KEY
is a valid column specification, it just doesn't specify a column named _id
.
When changing the schema like this, remember to bump up the database version number.
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