In my project I have to select multiple values and pass it to a query. i.e page1 contains checkboxes. I am storing the selected checkbox id's into an array.
I am shuffling that array and getting the values randomly. Now I need to pass these random values to a query. Using IN operator in database I can pass the values
statically but how can I pass the values dynamcially to the query.
For ex:(Passing values statically)
SELECT * FROM Persons WHERE person_id IN ('21','22')
In the above query the id's 21 and 22 are know previously and so we are passing statically but I want to send the values to query dynamically.
Page1:
public static ArrayList<String> chksublist = new ArrayList<String>();
Page2:
Collections.shuffle(chksublist );
SELECT * FROM Persons WHERE person_id IN ('21','22')
In the above line I want to send the random values which are in chksublist array.
String query = "SELECT * FROM Persons WHERE person_id IN (" + TextUtils.join(",", chksublist) + ")";
But shuffling the chksublist before sending it to your SQL query has no impact on the result set you get from SQL. It will not randomly permute your results. Remove Collections.shuffle(chksublist); and use
String query = "SELECT * FROM Persons WHERE person_id IN (" + TextUtils.join(",", chksublist) + ") ORDER BY RANDOM()";
see how values are dynamicaly passed
// Getting single contact
public Contact getContact(int id) {
SQLiteDatabase db = this.getReadableDatabase();
Cursor cursor = db.query(TABLE_CONTACTS, new String[] { KEY_ID,
KEY_NAME, KEY_PH_NO }, KEY_ID + "=?",
new String[] { String.valueOf(id) }, null, null, null, null);
// here new String[] { String.valueOf(id) } value is added dynamicaly which is passed to the function
if (cursor != null)
cursor.moveToFirst();
Contact contact = new Contact(Integer.parseInt(cursor.getString(0)),
cursor.getString(1), cursor.getString(2));
// return contact
return contact;
}
You can generate your query like this
int values[]; //it contains your generated values like 21,22....
String query="SELECT * FROM Persons WHERE person_id IN (";
for(int i=0;i<values.length;i++){
query=query+"'"+values[i]+"'";
if(i<values.length-1){
query=query+","; //No , after last values
}
}
query+=")";
finally pass this query.
Try it
cursor = database.query(tablename,
new String[] {"TopName"}, "id IN(?,?)", new String[]{"2","3"}, null, null, null);
using raw query
String query = "SELECT * FROM Persons WHERE person_id IN ("+parameter1+","+parameter2+")";
db.rawQuery(query);
Related
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();
I have a table with 3 columns "ID", "NAME" & "STATUS". I would like to execute a query on my database where I can get only one entry of "ID" which is located at the top row. I have a working sql query,
"SELECT TOP 1 ID from SAMPLE_TABLE WHERE Status='PENDING' ORDER BY ID ASC;"
This is so far what I implemented in android,
// Getting pending items
public int pendingContact() {
SQLiteDatabase db = this.getWritableDatabase();
Cursor mCount = db.query(
TABLE_CONTACTS ,
new String[] { "id" } ,
"status = ?" ,
new String[] { "PENDING" } ,
null ,
null ,
null
);
mCount.moveToFirst();
int count = mCount.getInt(0);
mCount.close();
return count;
}
Al through it gives the desired output but I would like to know if there is any other way of doing this more efficiently.
You can use Limit
public Cursor query (String table, String[] columns, String selection, String[] selectionArgs, String groupBy, String having, String orderBy, String limit)
limit - Limits the number of rows returned by the query, formatted as LIMIT clause. Passing null denotes no LIMIT clause.
You can do this:
Cursor mCount = db.query(TABLE_CONTACTS, new String[] { "id" }, "status = ?", new String[] { "PENDING" }, null, null, "id ASC", "1");
This will keep you from acquiring more data than you need.
When you use ORDER BY, the database will read and sort all PENDING items before it can return the first one.
When using MIN, nothing but the smallest value must be stored temporarily:
SELECT MIN(id) FROM Contacts WHERE Status = 'PENDING'
In code:
Cursor mCount = db.rawQuery("SELECT MIN(id) FROM Contacts WHERE Status = ?",
new String[] { "PENDING" });
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.
I have a table called food. I am selecting the "category" of the food item and I want to show it in a List View. This is the code I tried.
Cursor c = db.query(DATABASE_TABLE,
new String[] { "category" }, null, null, null, null, null);
ArrayList<ArrayList<String>> results = new ArrayList<ArrayList<String>>();
if(c.moveToFirst())
{
do
{ ArrayList<String> recipe = new ArrayList<String>();
recipe.add(c.getString(1));
recipe.add(c.getString(2));
recipe.add(c.getString(3));
recipe.add(c.getString(4));
results.add(recipe);
}while(c.moveToNext());
if(c != null && !c.isClosed())
c.close();
}
Try Now,
Cursor c = db.query(DATABASE_TABLE,
new String[] { "category" }, null, null, null, null, null);
ArrayList<String> results = new ArrayList<String>();
if(c.moveToFirst())
{
do
{
results.add(c.getString(0)); // instead of 0 Index of Category column in your case
}while(c.moveToNext());
if(c != null && !c.isClosed())
c.close();
}
From your database query You are selecting only category column so you have only one column result in cursor and its start with 0 index. So c.getString(1) to c.getString(4) is meaning less. If your select all data from table then only you get all columns..
I see your problem, you are only returning one column (category), yet you are trying to access several different ones.
You should be returning at least five (since you are trying to access up to 4 and the cursor columns start at 0).
If you are trying to pull a list of items with a certain category you need to change your query. Somethign like this :
String query = "SELECT * FROM " + DATABASE_TABLE + " WHERE category = " + category;
return mDb.rawQuery(query, null);
That will select all items that have a category matching whatever is contained in the variable category, and return all the coilumns in the row.
Hi all
I create a table like that
private static final String CREATE_TABLE_PRODUCT =
"create table prod (id integer primary key,titre text not null, desc text, is_free integer);";
i update it this way
SQLiteDatabase db = getConnection();
ContentValues updateEvent = new ContentValues();
updateEvent.put("is_free", 1);
int ok = db.update(prod, updateEvent, "id=?",
new String[] { Long.toString(evenement.getId()) });
db.close();
I do see the change in eclipse with DDMS questoid
but when i try to retrieve the value I get nothing ....
Cursor c = db.query(prod, new String[] { "id",
"titre", "desc", "is_free", },
"is_free=?", new String[] {"1"}, null, null,
null);
I've tried some variant like
String query = "SELECT * FROM "+EVENEMENT_TABLE+" WHERE is_free=1;";
Cursor c = sdb.rawQuery(query, null);
with no success
is this problem come from the type (integer) of my column ?
Any help
Do not use reserved keywords like desc in your queries. This probably causes query to fail.
In case you don't know update will not add values to the table. Use insert instead.