SQLite without NULL - android

I have been trying to get the biggest value of a column. For this I sorted it by DESC so the biggest one comes first, but it turns out that any nulls actually come first for some reason. Therefore I tried to add a WHERE, but it still has nulls in it for some reason and I can't figure out why.
String[] projection = {
DATAbaseContract.DATAbaseEntry.COLUMN_PRICE,
};
String sortOrder =
DATAbaseContract.DATAbaseEntry.COLUMN_PRICE + " DESC";
Cursor DATAbaseCursor = DATAbaseDb.query(
DATAbaseContract.DATAbaseEntry.TABLE_NAME, // The table to query
projection, // The columns to return
ShipsContract.ShipsEntry.COLUMN_PRICE + " IS NOT NULL", // The columns for the WHERE clause
null, // The values for the WHERE clause
null, // don't group the rows
null, // don't filter by row groups
sortOrder // The sort order
);
if(!DATAbaseCursor.moveToPosition(0)) {return;}
PriceMaxVal=DATAbaseCursor.getInt(DATAbaseCursor.getColumnIndex(DATAbaseContract.DATAbaseEntry.COLUMN_PRICE));
PriceMinVal=0;

Related

How to search multiple columns in SQLite db?

I got a problem when trying to search in multiple columns of a SQLite db.
Here ist my current code
String whereClause;
if (!suchwort.contains("%")){ // Abfrage mit Wildcard?
whereClause = WoerterbuchContract.WoerterbuchEintraege.COLUMN_NAME_WORT_DEUTSCH
+ " = '"+suchwort+"'" ;}
else {
whereClause = WoerterbuchContract.WoerterbuchEintraege.COLUMN_NAME_WORT_DEUTSCH
+" like '"+suchwort+"'";}
Cursor ergCursor = db.query(
WoerterbuchContract.WoerterbuchEintraege.TABLE_NAME, // The table to query
projection, // The columns to return
whereClause, // WHERE clause
null, // no values for the WHERE clause
null, // don't group the rows
null, // don't filter by row groups
sortOrder // The sort order
);
I tried adding columns to my whereClause, but i allways get compiler errors.

how to filter multiple data on multiple column sqlite database

i want to filter multiple data such as
id = "1,3,5" from columnid which is having 1 to 10 id
and another column such as name
name = "a,e,d" from name column of 10 records
and another criteria such as age
age = "21,23,20" from age column of 10 records from same table,
one example i got is
Cursor cursor = db.query("TABLE_NAME",new String[]{"ColumnName"}, "ColumnName=?",new String[]{"value"}, null, null, null);
which is just for one column but i want to get data from multiple column, can anyone help me?
try this working example,
Cursor cursor =
db.query(TABLE_DIARYENTRIES,
new String[] {},
STUDENT_ID + " IN ("+resultStudent+")"+ " AND " +CLASS_NAME + " IN ("+resultClass+")"
+ " AND " +SUBJECT_NAME + " IN ("+resultSubject+")"
null, null, null, null);
and your result string should be 'a','b','c'
I really like the way Google's example is structured. Because for noobies such as myself it makes it really clear what I am doing. And it is also more robust to SQL injections. Here is my modified version of the Google example:
//Column(s) I want returned
String[] projection = {"ColumnIWantReturned"};
//Column(s) I want to filer on
String selection = "FilterColumn1 IN (?) and FilterColumn2 IN (?, ?)";
String[] selectionArgs = {"ArgumentForFilterColumn1", "FirstArgumentForFilterColumn2", "SecondArgumentForFilterColumn2"};
Cursor cursor = db.query(
"MyTable", // The table to query
projection, // The array of columns to return (pass null to get all)
selection, // The columns for the WHERE clause
selectionArgs, // The values for the WHERE clause
null, // don't group the rows
null, // don't filter by row groups
null // The sort order
);
cursor.moveToFirst();
while (!cursor.isAfterLast()) {
Log.d("this-is-a-test", cursor.getString(0));
cursor.moveToNext();
}
cursor.close();

SQL Sorting number - ANDROID

public static final String KEY_HIGH
public void onCreate(SQLiteDatabase db) {
// TODO Auto-generated method stub
db.execSQL("CREATE TABLE " + DATABASE_TABLE + " (" +
KEY_HIGH + " INTERGE);"
);
}
public long createEntry(String high) {
ContentValues cv = new ContentValues();
cv.put(KEY_HIGH, high);
return ourDatabase.insert(DATABASE_TABLE, null, cv);
}
String[] columns = new String[]{KEY_HIGH,KEY_NAME};
Cursor c = ourDatabase.query(
DATABASE_TABLE,
columns, null, null, null, null, KEY_HIGH + " DESC");
I am trying to sort by the column KEY_HIGH, however, the result came out like this:
4
3
2
10
11
1
How do I sort them as numbers from highest to lowest?
thanks.
From the Android docs:
public Cursor query (String table, String[] columns, String selection, String[] selectionArgs, String groupBy, String having, String orderBy)
Added in API level 1
Query the given table, returning a Cursor over the result set.
Parameters
table The table name to compile the query against.
columns A list of which columns to return. Passing null will return all columns, which is discouraged to prevent reading data from storage that isn't going to be used.
selection A filter declaring which rows to return, formatted as an SQL WHERE clause (excluding the WHERE itself). Passing null will return all rows for the given table.
selectionArgs You may include ?s in selection, which will be replaced by the values from selectionArgs, in order that they appear in the selection. The values will be bound as Strings.
groupBy A filter declaring how to group rows, formatted as an SQL GROUP BY clause (excluding the GROUP BY itself). Passing null will cause the rows to not be grouped.
having A filter declare which row groups to include in the cursor, if row grouping is being used, formatted as an SQL HAVING clause (excluding the HAVING itself). Passing null will cause all row groups to be included, and is required when row grouping is not being used.
orderBy How to order the rows, formatted as an SQL ORDER BY clause (excluding the ORDER BY itself). Passing null will use the default sort order, which may be unordered.
Returns
A Cursor object, which is positioned before the first entry. Note that Cursors are not synchronized, see the documentation for more details.
See Also
Cursor
Note that the final is named orderBy. This is where you can specify which column (or columns) to sort on. Also note that you do not need to include the "ORDER BY" keywords that you would use in a SQL statement.
I was having the same problem.It has a very simple solution:
In your CREATE_TABLE statement do this: " INTEGER, "+KEY_HIGH+ //your remaining things.
no need for the comma after the last null
Cursor c = ourDatabase.query(
DATABASE_TABLE,
columns, null, null, null, null + " ORDER BY " + KEY_HIGH + " DESC");

Update row in SQlite database by row position in android

I have database which contains "date" column and "item" column.
I want that user could update specific row in the database.
I trying to do it with update method in SQLiteDatabase class.
My problem is that i dont know how to make update method find exactly the row i want.
I saw some example that use it with parameters from one word.
like this:
ourDatabase.update(tableName, cvUpdate, rowId + "=" + item , null);
My problem is that i want to update the row that have specific item and date. so the name of the item alone is not enough.
I tried this code below but its didnt work, hope youll can help me.
public void updateEntry(String item, String date) throws SQLException{
String[] columns = new String[]{myItem, myDate};
Cursor c = ourDatabase.query(tableName, columns, null, null, null, null, null);
long position;
ContentValues cvUpdate = new ContentValues();
cvUpdate.put(date, myDate);
cvUpdate.put(item, myExercise);
int itemAll = c.getColumnIndex(myItem);
int dateAll = c.getColumnIndex(myDate);
for (c.moveToFirst(); !c.isAfterLast(); c.moveToNext()){
if (c.getString(itemAll).equals(myItem) && c.getString(dateAll).equals(myDate))
{
position = c.getPosition();
break;
}
}
ourDatabase.update(tableName, cvUpdate, rowId + "=" + position , null);
}
First, the columns String[] is supposed to contain column names, such as "_ID", or whatever are the column names you have used. Given that you compare the content of the column myItem with the object myItem, I assume there is a confusion somewhere here.
Secondly, rowId and position are different things in SQL, especially if you delete rows, as the row id usually is autoincrement, and especially since your query is not explicitely sorted. Replacing c.getPosition() by c.getLong(c.getColumnIndex(ID_COLUMN)) would make more sense.
Thirdly, sql is nice because you can query it. For example, rather than get all items and loop to find the matching date and item, you can :
String whereClause = ITEM_COLUMN + " = ? and " + DATE_COLUMN + " = ?";
String[] whereArgs = new String[] { item, date };
Cursor c = ourDatabase.query(tableName, columns, whereClause, whereArgs, null, null, null);
instead of your for loop.
Forthly, you can even make the query in the update :
String whereClause = ITEM_COLUMN + " = ? and " + DATE_COLUMN + " = ?";
String[] whereArgs = new String[] { item, date };
ourDatabase.update(tableName, cvUpdate, whereClause, whereArgs);
Extra tip: use full caps variable names for contants such as column names, it help with readability.

Multiple OrderBy in SQLiteDatabase.Query Method

I am using the query method of SQLiteDatabase. I need help with the orderBy parameter of this method.
Cursor cursor = sqLiteDatabase.query(tableName, tableColumns, whereClause, whereArgs, groupBy, having, orderBy);
public Cursor getAllCustomexp(int TID) throws SQLException
{
Cursor mCursor =
db.query(false, CEXP_TABLE, new String[] {KEY_CEID, FLD_CETID, FLD_CEEID, FLD_CEMID,
FLD_CEAMT, FLD_CESEL}, FLD_CETID + " = " + TID, null,
null, null, FLD_CEEID, null);
if (mCursor != null) {
mCursor.moveToFirst();
}
return mCursor;
}
Question 1:
In the above query the result set will be sorted by FLD_CEEID in ascending or descending order ?
Question 2:
If I need to order the result set first by FLD_CEEID and then by FLD_CEMID how should i construct the order by parameter of this query.
Is it possible to do multiple order by using this method?
From SQLite docs:
If a SELECT statement that returns more than one row does not have an
ORDER BY clause, the order in which the rows are returned is
undefined. Or, if a SELECT statement does have an ORDER BY clause,
then the list of expressions attached to the ORDER BY determine the
order in which rows are returned to the user. Rows are first sorted
based on the results of evaluating the left-most expression in the
ORDER BY list, then ties are broken by evaluating the second left-most
expression and so on. The order in which two rows for which all ORDER
BY expressions evaluate to equal values are returned is undefined.
Each ORDER BY expression may be optionally followed by one of the
keywords ASC (smaller values are returned first) or DESC (larger
values are returned first). If neither ASC or DESC are specified, rows
are sorted in ascending (smaller values first) order by default.
Answer 1: Result set will be sorted in ascending order.
Answer 2:
String orderBy = FLD_CEEID + " ASC, " + FLD_CEMID + " ASC";
db.query(false, CEXP_TABLE, new String[] {KEY_CEID, FLD_CETID, FLD_CEEID, FLD_CEMID,
FLD_CEAMT, FLD_CESEL}, FLD_CETID + " = " + TID, null,
null, null, orderBy, null);
It works like in SQL Select Order By. You can find details here: http://en.wikipedia.org/wiki/Order_by_(SQL) .

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