我是数据库新手，请多多包涵。我试图将我的数据库设置为创建条目时，它在 ListView 中显示为创建日期(例如，“2011 年 12 月 23 日”)，然后您可以单击它并查看您拥有的所有内容那天创建的。这是我目前所拥有的:
public class DbAdapter
{
private static final String TAG = "DbAdapter";
private DatabaseHelper mDbHelper;
private SQLiteDatabase mDb;
private static final String DATABASE_CREATE =
"create table entry (_id integer primary key autoincrement, "
+ "date text UNIQUE, " +
"velocity integer not null, " +
"type text not null, " +
"xCoord real not null, " +
"yCoord real not null, " +
"color integer not null);";
private static final String DATABASE_NAME = "data";
private static final String DATABASE_TABLE = "entry";
private static final int DATABASE_VERSION = 2;
private final Context mCtx;
private SQLiteStatement insertStmt;
private static final String INSERT = "insert into " + DATABASE_TABLE + "(date) values (?)";
private static class DatabaseHelper extends SQLiteOpenHelper
{
DatabaseHelper(Context context)
{
super(context, DATABASE_NAME, null, DATABASE_VERSION);
}
@Override
public void onCreate(SQLiteDatabase db)
{
db.execSQL(DATABASE_CREATE);
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion)
{
Log.w(TAG, "Upgrading database from version " + oldVersion + " to "
+ newVersion + ", which will destroy all old data");
db.execSQL("DROP TABLE IF EXISTS entry");
onCreate(db);
}
}
public DbAdapter(Context ctx)
{
this.mCtx = ctx;
}
public DbAdapter open() throws SQLException
{
mDbHelper = new DatabaseHelper(mCtx);
mDb = mDbHelper.getWritableDatabase();
this.insertStmt = this.mDb.compileStatement(INSERT);
return this;
}
public void close()
{
mDbHelper.close();
}
public long addEntry(String date, int velocity, String type, float xCoord, float yCoord, int color)
{
ContentValues initialValues = new ContentValues();
initialValues.put("date", date);
initialValues.put("velocity", velocity);
initialValues.put("type", type);
initialValues.put("xCoord", xCoord);
initialValues.put("yCoord", yCoord);
initialValues.put("color", color);
return mDb.insert(DATABASE_TABLE, null, initialValues);
}
public boolean deleteEntry(long rowId)
{
return mDb.delete(DATABASE_TABLE, "_id" + "=" + rowId, null) > 0;
}
public Cursor fetchAllEntries()
{
return mDb.query(DATABASE_TABLE, new String[] {"_id", "date", "velocity",
"type", "xCoord", "yCoord", "color"}, null, null, null, null, null);
}
public Cursor fetchEntry(long rowId) throws SQLException
{
Cursor mCursor = mDb.query(true, DATABASE_TABLE, new String[] {"_id", "date",
"velocity", "type"}, "_id" + "=" + rowId, null,
null, null, null, null);
if (mCursor != null)
{
mCursor.moveToFirst();
}
return mCursor;
}
public Cursor fetchInfo(long rowId) throws SQLException
{
Cursor mCursor = mDb.query(true, DATABASE_TABLE, new String[] {"_id", "velocity", "xCoord", "yCoord", "color"}, "_id" + "=" + rowId, null, null, null, null, null);
if(mCursor != null)
{
mCursor.moveToFirst();
}
return mCursor;
}
}
这对于我创建的第一个条目来说工作正常，但我无法为那一天创建更多条目，它给我一个错误提示:
12-23 09:22:16.460: E/Database(272): Error inserting velocity=17 yCoord=121.0 xCoord=344.0 color=3 type=UNFINISHED date=December 23, 2011
12-23 09:22:16.460: E/Database(272): android.database.sqlite.SQLiteConstraintException: error code 19: constraint failed
12-23 09:22:16.460: E/Database(272): at android.database.sqlite.SQLiteStatement.native_execute(Native Method)
12-23 09:22:16.460: E/Database(272): at android.database.sqlite.SQLiteStatement.execute(SQLiteStatement.java:55)
12-23 09:22:16.460: E/Database(272): at android.database.sqlite.SQLiteDatabase.insertWithOnConflict(SQLiteDatabase.java:1549)
12-23 09:22:16.460: E/Database(272): at android.database.sqlite.SQLiteDatabase.insert(SQLiteDatabase.java:1410)
12-23 09:22:16.460: E/Database(272): at com.x17.projects.strikezone.DbAdapter.addEntry(DbAdapter.java:96)
12-23 09:22:16.460: E/Database(272): at com.x17.projects.strikezone.Tab1$2.onClick(Tab1.java:121)
12-23 09:22:16.460: E/Database(272): at com.android.internal.app.AlertController$ButtonHandler.handleMessage(AlertController.java:158)
12-23 09:22:16.460: E/Database(272): at android.os.Handler.dispatchMessage(Handler.java:99)
12-23 09:22:16.460: E/Database(272): at android.os.Looper.loop(Looper.java:123)
12-23 09:22:16.460: E/Database(272): at android.app.ActivityThread.main(ActivityThread.java:4627)
12-23 09:22:16.460: E/Database(272): at java.lang.reflect.Method.invokeNative(Native Method)
12-23 09:22:16.460: E/Database(272): at java.lang.reflect.Method.invoke(Method.java:521)
12-23 09:22:16.460: E/Database(272): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)
12-23 09:22:16.460: E/Database(272): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
12-23 09:22:16.460: E/Database(272): at dalvik.system.NativeStart.main(Native Method)
我知道发生此错误是因为我试图将一个值插入到已有值的行中。所以我的问题是，如何在创建日期内插入多个值。我有一个没有被使用的插入语句，因为我不知道在哪里以及如何使用它，我不确定它是否正确。由于我是新手，所以只要指出正确的方向就会有所帮助。
提前致谢。
更新: 我从所有列中删除了“not null”并将我的插入语句更改为:
private static final String INSERT = "INSERT INTO " + DATABASE_TABLE + "(date, velocity, type, xCoord, yCoord, color) VALUES (?,?,?,?,?,?)";
我正在插入这样的值:
public long addEntry(String date, int velocity, String type, float xCoord, float yCoord, int color)
{
this.insertStmt.bindString(1, date);
this.insertStmt.bindLong(2, velocity);
this.insertStmt.bindString(3, type);
this.insertStmt.bindDouble(4, xCoord);
this.insertStmt.bindDouble(5, yCoord);
this.insertStmt.bindLong(6, color);
return this.insertStmt.executeInsert();
}
我仍然收到相同的“错误代码 19:约束失败”错误。
12-23 11:36:03.343: E/AndroidRuntime(418): FATAL EXCEPTION: main
12-23 11:36:03.343: E/AndroidRuntime(418): android.database.sqlite.SQLiteConstraintException: error code 19: constraint failed
12-23 11:36:03.343: E/AndroidRuntime(418): at android.database.sqlite.SQLiteStatement.native_execute(Native Method)
12-23 11:36:03.343: E/AndroidRuntime(418): at android.database.sqlite.SQLiteStatement.executeInsert(SQLiteStatement.java:81)
12-23 11:36:03.343: E/AndroidRuntime(418): at com.x17.projects.strikezone.DbAdapter.addEntry(DbAdapter.java:86)
12-23 11:36:03.343: E/AndroidRuntime(418): at com.x17.projects.strikezone.Tab1$2.onClick(Tab1.java:120)
12-23 11:36:03.343: E/AndroidRuntime(418): at com.android.internal.app.AlertController$ButtonHandler.handleMessage(AlertController.java:158)
12-23 11:36:03.343: E/AndroidRuntime(418): at android.os.Handler.dispatchMessage(Handler.java:99)
12-23 11:36:03.343: E/AndroidRuntime(418): at android.os.Looper.loop(Looper.java:123)
12-23 11:36:03.343: E/AndroidRuntime(418): at android.app.ActivityThread.main(ActivityThread.java:4627)
12-23 11:36:03.343: E/AndroidRuntime(418): at java.lang.reflect.Method.invokeNative(Native Method)
12-23 11:36:03.343: E/AndroidRuntime(418): at java.lang.reflect.Method.invoke(Method.java:521)
12-23 11:36:03.343: E/AndroidRuntime(418): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)
12-23 11:36:03.343: E/AndroidRuntime(418): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
12-23 11:36:03.343: E/AndroidRuntime(418): at dalvik.system.NativeStart.main(Native Method)
我做错了什么？
最佳答案
我怀疑“日期文本 UNIQUE”对您来说是个问题，如果您删除 UNIQUE，那么您应该能够插入具有相同日期的多个条目——如果我对您的理解正确的话。
问题 2:如果您将数据库中的字段设置为“not null”，那么您必须在“insert”语句中为这些字段指定值。目前，您仅在 insert 语句中设置日期字段。因此，您要么需要在“insert”语句中为所有字段指定值，要么需要删除表创建中的“not null”规范。
要获取 ListView 的日期，您需要执行某种SELECT 查询，可能按日期字段分组，因此每个日期只能获取一行。这样的事情应该有效:
SELECT * from table GROUP BY date
关于android - 如何查看特定日期的所有条目，SQLite - Android，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/8617342/