Develop Reference

android sqlite string parameter value not working [duplicate]

I'm trying to select some data from database and I have two slices of code to do it:
cursor = builder.query(db,
new String[]{"col1", "col2", "col3"},
"id = ?", new String[]{getSID(db)}, null, null, null);
and
cursor = builder.query(db,
new String[]{"col1", "col2", "col3"},
"id = " + getSID(db), null, null, null, null);
The difference between them is that first one seems to be more correct according to documentation, but it also doesn't work - cursor is empty. Instead of the second one - I'm getting all data I need.
So I tried to execute different SQL queries on my PC with a copy of database and that's what I've got:
SELECT col1, col2, col3 FROM SomeTables WHERE (id = '42')
This one doesn't work (and this query obviously equals to query, generated by first code sample)
SELECT col1, col2, col3 FROM SomeTables WHERE (id = 42)
And this one works fine (equals to query from second code sample).
As I know, SQLite should perform type cast automatically, but something went wrong and I don't know why. Do you have any ideas about how first code sample can be fixed? (Or, perhaps, database?)
If it matters, here's simplified CREATE script of the table with id field:
CREATE TABLE SomeTable ( ID PRIMARY KEY, col1, col2, [...] )
UPD: And, by the way, getSID(db) returns String Object.

That query parameters can only be strings is a horrible design error in the Android database API.
Despite what the documentation says, you should use parameters only for actual string values; integer values can be safely embedded directly into the SQL string. (For blobs, you must use a function that accepts ContentValues.)
Please note that while SQLite uses dynamic typing, values of different types do not compare equal in most cases (SELECT 42='42'; returns 0).
There are some cases where SQLite does automatically convert values due to type affinity (in your case, this would happen if you declared the id column as INTEGER), but this is rather counterintuitive, so it should not be relied upon.

According to SQLite documentation,
Any column in an SQLite version 3 database, except an INTEGER PRIMARY KEY column, may be used to store a value of any storage class.
In context of my case, that means that we can't be sure what data type will be stored in columns. If you can control and convert data types when they're putting into database - you can convert id values to TEXT when adding data to database and use selectionArgs easily. But it's not an answer for my question, because I have to deal with database content as is.
So, possible solutions:
a) embed integer values in selection string without wrapping them into ':
cursor = builder.query(db,
new String[]{"col1", "col2", "col3"},
"id = " + getSID(db), null, null, null, null);
b) cast values from selectionArgs: CAST(? as INTEGER) or CAST(id AS TEXT). I think, converting column to TEXT is better solution, because right operand is always TEXT, but the left one can be anything. So:
cursor = builder.query(db,
new String[]{"col1", "col2", "col3"},
"CAST(id AS TEXT) = ?",
new String[]{getSID(db)}, null, null, null);

You need to convert your int id into string before passing to your query because the parameter array is of type string. For example:
cursor = builder.query(db, new String[]{"col1", "col2", "col3"},
"id = ?", new String[]{String.valueOf(getSID(db))}, null, null, null);
The reason why it works in second type of query is because you are appending the integer value with string which automatically converts the int into String. For example:
int i = 10;
String s = i + ""; //now 10 is in string

Android Sql. Query single coloumn, multiple values

I have database with three columns.
I would like to query the database, based on one column which can have multiple values.
For single parameter we can the normal query method where cardName is String[]
Cursor cursor = database.query(Database.TABLE_COUPON_CARD, allColumns,Database.COLUMN_CARD_NAME + " = ?", cardName, null, null,null);
but if there are more than one value, I get a Android SQLite cannot bind argument exception
For multiple values of the same column we can use IN statement but, here how do I write the QUERY or how should i form the rawQuery
String whereClause = Database.COLUMN_CARD_NAME+ " IN(?)";
Cursor cursor = database.query(Database.TABLE_COUPON_CARD, allColumns,whereClause,new String[][]{cardName}, null, null,null);
Android QUERY doesnot take array of array.
What should the correct query be?
TEMPORARY SOLUTION
Currently I have created a method which dynamically creates the clause.
private static StringBuilder buildInClause(String[] myStringArray){
StringBuilder fullString=new StringBuilder();
fullString.append("(");
for(int i=0;i<myStringArray.length;i++){
fullString.append(" '"+myStringArray[i]+"' ");
if(i!=myStringArray.length-1){
fullString.append(",");
}
}
fullString.append(")");
return fullString;
}
If anyone has any other solution please do share.

For two values: IN(?,?). For three values: IN(?,?,?). Get the idea? Each ? corresponds to a single literal in the selection args array.

Understanding SQLite Cursor Behavior

I'm writing a method to update default settings in a table. The table is very simple: two columns, the first containing labels to indicate the type of setting, the second to store the value of the setting.
At this point in the execution, the table is empty. I'm just setting up the initial value. So, I expect that this cursor will come back empty. But instead, I'm getting an error (shown below). The setting that I am working with is called "lastPlayer" and is supposed to get stored in the "SETTING_COLUMN" in the "SETTINGS_TABLE". Here's the code:
public static void updateSetting(String setting, String newVal) {
String table = "SETTINGS_TABLE";
String[] resultColumn = new String[] {VALUE_COLUMN};
String where = SETTING_COLUMN + "=" + setting;
System.err.println(where);
SQLiteDatabase db = godSimDBOpenHelper.getWritableDatabase();
Cursor cursor = db.query(table, resultColumn, where, null, null, null, null);
System.err.println("cursor returned"); //I never see this ouput
\\more
}
sqlite returned: error code = 1, msg = no such column: lastPlayer
Why is it saying that there is no such column lastPlayer? I thought that I was telling the query to look at the column "SETTING_COLUMN" and return the record where that column has a value "lastPlayer". I'm confused. Can somebody straighten me out? I've been looking a this for an hour and I just don't see what I am doing wrong.
Thanks!

You're not properly building/escaping your query. Since the value lastPlayer is not in quotes, your statement is checking for equality of two columns, which is what that error message is saying.
To properly build your query, it's best to not do this manually with String concatenation. Instead, the parameter selectionArgs of SQLiteDatabase.query() is meant to do this.
The parameters in your query should be defined as ? and then filled in based on the selectionArgs. From the docs:
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.
So, your code would look like this:
String where = SETTING_COLUMN + " = ?";
Cursor cursor = db.query(table, resultColumn, where, new String[] { setting }, null, null, null);

What is the correct syntax for SELECT statement and WHERE clause?

I am trying to explore android and I just started using SQLite database. I'm wondering on what is the right syntax for selecting a single row from a table, where the row I want to select is from the value entered from a user using editText. Thanks in advance.

I'm going to disagree with both of the answers above. What if the user enters this query:
Bobby Tables'; drop table yourTable;
See: http://xkcd.com/327/
I believe you should do this instead:
String query = "select * from TABLE_NAME WHERE column_name=?";
String[] selection = new String[1];
selection[0] = users_entered_value;
Cursor c = db.rawQuery(query, selection);
ETA: Actually, the more I think about it, the more I think you're going in the wrong direction. If your app depends on a database query returning exactly one unique match to an arbitrary string entered by the user, it's probably going to be broken a great deal of the time.
What you should probably do is something like this:
String query = "select * from TABLE_NAME WHERE column_name LIKE ?";
String[] selection = new String[1];
selection[0] = "%" + users_entered_value + "%";
Cursor c = db.rawQuery(query, selection);
and then iterate through the results and pick a "best" match according to your own criteria.
Also, you should create the table with case-insensitive matching for the column(s) you're going to be searching.

SQLiteDatabase db;
db.rawQuery("select * from yourTable where your_column_name = 'users_entered_value' limit 1", null);

SQLiteDatabase db;
// make connection to your database ;
Cursor c = null ;
String SQL = "select * from TABLE_NAME where column_name='VALUE'";
c = db.rawQuery(SQL);
c contains your result array of query you fired.
You can retrieve values using loop.

SQLite Database Problem while delete

Hi to All I am new to Android.
I am using SQLite DataBase in my Application
meanwhile I am Written Queries using +
Like delete from tablename where value = + value;
this is my query
String delete_query = "delete from " + tableName
+ " where title = '" + title + "'";
database.execSQL(delete_query);
I want to write this Query using placeholder ?.
so that i tried
database.delete(tableName, title + "?" , new String[] {title});
instead "?" i tried (?)/('?')/'?'
but it is giving me an error....
can any one tell me how to write appropriate query using ?.....
Thanks in Advance.
Mahaveer

Make sure you have put the equal sign:-
database.delete(tableName, title + "=?" , new String[] {title});

As far as possible, try to use the less raw queries you can. Two advantages:
Query parameters will be escaped by the system (protection against SQL injection)
The code will be more readable
See the delete function of SQLiteDatabase class
public int delete (String table, String whereClause, String[]
whereArgs)
Convenience method for deleting rows in the
database.
table the table to delete from
whereClause the optional WHERE clause
to apply when deleting. Passing null will delete all rows.
Returns the number of rows affected if a whereClause is passed in, 0
otherwise. To remove all rows and get a count pass "1" as the
whereClause.
In your case:
final String where = "title=?";
final String[] args = new String[] { title };
database.delete(tableName, where, args);