我有这个代码，应该在通过检查其isbn数字
添加图书之前进行搜索这是我的Dbhelper类中的isExist方法
public boolean isExist(String isbnNo)
{
SQLiteDatabase db;
db = this.getWritableDatabase();
String query= "SELECT * FROM "+TABLE_NAME +"WHERE "+KEY_ISBN+"='"+isbnNo+"'";
Cursor cursor=db.rawQuery(query, null);
if(cursor.getCount()<1) // UserName Not Exist
{
cursor.close();
return true;
}
else
{
cursor.close();
return false;
}
}
这是我的添加活动类
中的添加方法private void saveData(){
dataBase=mHelper.getWritableDatabase();
ContentValues values=new ContentValues();
DbHelper dbHelper = new DbHelper(getApplicationContext());
values.put(DbHelper.KEY_NAME,name);
values.put(DbHelper.KEY_AUTHOR,author );
values.put(DbHelper.KEY_ISBN,isbn );
values.put(DbHelper.KEY_COPIES,copy );
values.put(DbHelper.KEY_INFO,info );
System.out.println("");
if(isUpdate)
{
//update database with new data
dataBase.update(DbHelper.TABLE_NAME, values, DbHelper.KEY_ID+"="+id, null);
}
else
{
//insert data into database
if(!dbHelper.isExist(isbn))
dataBase.insert(DbHelper.TABLE_NAME, null, values);
else
Toast.makeText(getApplicationContext(), "already exist", Toast.LENGTH_LONG).show();
}
//close database
dataBase.close();
finish();
}
onClick方法
public void onClick(View v) {
name=edit_name.getText().toString().trim();
author=edit_author.getText().toString().trim();
isbn=edit_isbn.getText().toString().trim();
copy=edit_copy.getText().toString().trim();
info=edit_info.getText().toString().trim();
if(name.length()>0 && author.length()>0 && isbn.length()>0 && copy.length()>0 && info.length()>0)
{
saveData();
}
else
{
AlertDialog.Builder alertBuilder=new AlertDialog.Builder(AdminAddBook.this);
alertBuilder.setTitle("Invalid Data");
alertBuilder.setMessage("Please, Enter valid data");
alertBuilder.setPositiveButton("Ok", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int which) {
dialog.cancel();
}
});
alertBuilder.create().show();
}
}
我得到的logcat
12-20 11:39:25.160: I/Choreographer(900): Skipped 151 frames! The application may be doing too much work on its main thread.
12-20 11:39:25.200: D/gralloc_goldfish(900): Emulator without GPU emulation detected.
12-20 11:39:25.640: I/Choreographer(900): Skipped 39 frames! The application may be doing too much work on its main thread.
12-20 11:39:36.770: D/dalvikvm(900): GC_FOR_ALLOC freed 126K, 7% free 3083K/3284K, paused 83ms, total 100ms
12-20 11:39:48.430: I/Choreographer(987): Skipped 44 frames! The application may be doing too much work on its main thread.
12-20 11:39:48.500: D/gralloc_goldfish(987): Emulator without GPU emulation detected.
12-20 08:40:02.735: D/dalvikvm(987): GC_FOR_ALLOC freed 123K, 7% free 3079K/3280K, paused 111ms, total 117ms
12-20 08:40:02.775: I/Choreographer(987): Skipped 43 frames! The application may be doing too much work on its main thread.
12-20 08:40:05.815: I/Choreographer(987): Skipped 49 frames! The application may be doing too much work on its main thread.
12-20 08:40:13.965: D/dalvikvm(987): GC_FOR_ALLOC freed 112K, 6% free 3243K/3432K, paused 87ms, total 130ms
12-20 08:40:14.305: I/Choreographer(987): Skipped 238 frames! The application may be doing too much work on its main thread.
12-20 08:40:14.565: I/Choreographer(987): Skipped 46 frames! The application may be doing too much work on its main thread.
12-20 08:40:25.535: I/Choreographer(987): Skipped 112 frames! The application may be doing too much work on its main thread.
12-20 08:40:32.085: D/dalvikvm(987): GC_FOR_ALLOC freed 97K, 5% free 3660K/3832K, paused 33ms, total 39ms
12-20 08:40:42.495: E/SQLiteLog(987): (1) near "=": syntax error
12-20 08:40:42.495: D/AndroidRuntime(987): Shutting down VM
12-20 08:40:42.505: W/dalvikvm(987): threadid=1: thread exiting with uncaught exception (group=0xb4a57b90)
12-20 08:40:42.525: E/AndroidRuntime(987): FATAL EXCEPTION: main
12-20 08:40:42.525: E/AndroidRuntime(987): Process: com.example.mobilib, PID: 987
12-20 08:40:42.525: E/AndroidRuntime(987): android.database.sqlite.SQLiteException: near "=": syntax error (code 1): , while compiling: SELECT * FROM BookWHERE isbn='123'
12-20 08:40:42.525: E/AndroidRuntime(987): at android.database.sqlite.SQLiteConnection.nativePrepareStatement(Native Method)
12-20 08:40:42.525: E/AndroidRuntime(987): at android.database.sqlite.SQLiteConnection.acquirePreparedStatement(SQLiteConnection.java:889)
12-20 08:40:42.525: E/AndroidRuntime(987): at android.database.sqlite.SQLiteConnection.prepare(SQLiteConnection.java:500)
12-20 08:40:42.525: E/AndroidRuntime(987): at android.database.sqlite.SQLiteSession.prepare(SQLiteSession.java:588)
12-20 08:40:42.525: E/AndroidRuntime(987): at android.database.sqlite.SQLiteProgram.<init>(SQLiteProgram.java:58)
12-20 08:40:42.525: E/AndroidRuntime(987): at android.database.sqlite.SQLiteQuery.<init>(SQLiteQuery.java:37)
12-20 08:40:42.525: E/AndroidRuntime(987): at android.database.sqlite.SQLiteDirectCursorDriver.query(SQLiteDirectCursorDriver.java:44)
12-20 08:40:42.525: E/AndroidRuntime(987): at android.database.sqlite.SQLiteDatabase.rawQueryWithFactory(SQLiteDatabase.java:1314)
12-20 08:40:42.525: E/AndroidRuntime(987): at android.database.sqlite.SQLiteDatabase.rawQuery(SQLiteDatabase.java:1253)
12-20 08:40:42.525: E/AndroidRuntime(987): at com.example.mobilib.DbHelper.isExist(DbHelper.java:37)
12-20 08:40:42.525: E/AndroidRuntime(987): at com.example.mobilib.AdminAddBook.saveData(AdminAddBook.java:146)
12-20 08:40:42.525: E/AndroidRuntime(987): at com.example.mobilib.AdminAddBook.onClick(AdminAddBook.java:106)
12-20 08:40:42.525: E/AndroidRuntime(987): at android.view.View.performClick(View.java:4424)
12-20 08:40:42.525: E/AndroidRuntime(987): at android.view.View$PerformClick.run(View.java:18383)
12-20 08:40:42.525: E/AndroidRuntime(987): at android.os.Handler.handleCallback(Handler.java:733)
12-20 08:40:42.525: E/AndroidRuntime(987): at android.os.Handler.dispatchMessage(Handler.java:95)
12-20 08:40:42.525: E/AndroidRuntime(987): at android.os.Looper.loop(Looper.java:137)
12-20 08:40:42.525: E/AndroidRuntime(987): at android.app.ActivityThread.main(ActivityThread.java:4998)
12-20 08:40:42.525: E/AndroidRuntime(987): at java.lang.reflect.Method.invokeNative(Native Method)
12-20 08:40:42.525: E/AndroidRuntime(987): at java.lang.reflect.Method.invoke(Method.java:515)
12-20 08:40:42.525: E/AndroidRuntime(987): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:777)
12-20 08:40:42.525: E/AndroidRuntime(987): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:593)
12-20 08:40:42.525: E/AndroidRuntime(987): at dalvik.system.NativeStart.main(Native Method)
我遇到的问题是，当我点击我的保存按钮时，应用程序将崩溃
有人可以帮我查一下吗？
谢谢！
答案 0 :(得分：0)
你需要在书和sql字符串中的位置之间留一个空白。
答案 1 :(得分：0)
尝试这样：
您的查询有错误，如表名和克劳斯之间没有空格。
public boolean isExist(String isbnNo)
{
SQLiteDatabase db;
db = this.getWritableDatabase();
String query= "SELECT * FROM "+TABLE_NAME +" WHERE "+KEY_ISBN+"='"+isbnNo+"'";
Cursor cursor=db.rawQuery(query, null);
if(cursor.getCount()<1) // UserName Not Exist
{
cursor.close();
return true;
}
else
{
cursor.close();
return false;
}
}