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• SELECT subset from two tables and LEFT JOIN results

  - by Doctor Trout

  Hi all, I'm trying to write a bit of SQL for SQLITE that will take a subset from two tables (TableA and TableB) and then perform a LEFT JOIN. This is what I've tried, but this produces the wrong result: Select * from TableA Left Join TableB using(key) where TableA.key2 = "xxxx" AND TableB.key3 = "yyyy" This ignore cases where key2="xxxx" but key3 != "yyyy". I want all the rows from TableA that match my criteria whether or not their corresponding value in TableB matches, but only those rows from TableB that match both conditions. I did manage to solve this by using a VIEW, but I'm sure there must be a better way of doing this. It's just beginning to drive me insane tryng to solve it now. (Thanks for any help, hope I've explained this well enough).

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• Database indexes and their Big-O notation

  - by miket2e

  I'm trying to understand the performance of database indexes in terms of Big-O notation. Without knowing much about it, I would guess that: Querying on a primary key or unique index will give you a O(1) lookup time. Querying on a non-unique index will also give a O(1) time, albeit maybe the '1' is slower than for the unique index (?) Querying on a column without an index will give a O(N) lookup time (full table scan). Is this generally correct ? Will querying on a primary key ever give worse performance than O(1) ? My specific concern is for SQLite, but I'd be interested in knowing to what extent this varies between different databases too.

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• Is re-using a Command and Connection object in ado.net a legitimate way of reducing new object creat

  - by Neil Trodden

  The current way our application is written, involves creating a new connection and command object in every method that access our sqlite db. Considering we need it to run on a WM5 device, that is leading to hideous performance. Our plan is to use just one connection object per-thread but it's also occurred to us to use one global command object per-thread too. The benefit of this is it reduces the overhead on the garbage collector created by instantiating objects all over the place. I can't find any advice against doing this but wondered if anyone can answer definitively if this is a good or bad thing to do, and why?

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• Sqlite iPhone data insertion problem

  - by Asad Khan

  Hi I have a function which basically tries to insert some data returned from a REST call. - (void)syncLocalDatabase{ NSString *file = [[NSBundle mainBundle] pathForResource:@"pickuplines" ofType:@"db"]; NSMutableString *query = [[NSMutableString alloc] initWithFormat:@""]; sqlite3 *database = NULL; char *errorMsg = NULL; if (sqlite3_open([file UTF8String], &database) == SQLITE_OK) { for(PickUpLine *pickupline in pickUpLines){ [query appendFormat:@"INSERT INTO pickuplines VALUES(%d,%d,%d,'%@','YES')", pickupline.line_id, pickupline.thumbsUps, pickupline.thumbsDowns, [pickupline.line stringByReplacingOccurrencesOfString:@"'" withString:@"`"]]; NSLog(query); int result = sqlite3_exec(database, [query UTF8String], NULL, NULL, &errorMsg); if (result!=SQLITE_OK) { printf("\n%s",errorMsg); sqlite3_free(errorMsg); } //sqlite3_step([query UTF8String]); [query setString:@""]; }//end for }//end if [query release]; sqlite3_close(database); } everything seems fine query string in log statement is also fine but the data does not gets inserted. Where as a counterpart of this function for select statement works well. Here is the counter part - (void)loadLinesFromDatabase{ NSString *file = [[NSBundle mainBundle] pathForResource:@"pickuplines" ofType:@"db"]; sqlite3 *database = NULL; if (sqlite3_open([file UTF8String], &database) == SQLITE_OK) { sqlite3_exec(database, "SELECT * FROM pickuplines", MyCallback, linesFromDatabase, NULL); } sqlite3_close(database); } I have implemented callback & it works fine. I am a little new to Sqlite can someone please point out what am I doing wrong. Thanx

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• retrieve columns from sqlite3

  - by John Smith

  I have two tables in sqlite: CREATE TABLE fruit ('fid' integer, 'name' text); CREATE TABLE basket ('fid1' integer, 'fid2' integer, 'c1' integer, 'c2' integer); basket is supposed to have count c1 of fruit fid1 and c2 of fruit fid2 I created a view fruitbasket; create view fruitbasket as select * from basket inner join fruit a on a.fid=basket.fid1 inner join fruit b on b.fid=basket.fid2; it works (almost) as expected. When I type pragma table_info(fruitbasket); I get the following output 0|fid1|integer|0||0 1|fid2|integer|0||0 2|c1|integer|0||0 3|c2|integer|0||0 4|fid|integer|0||0 5|name|text|0||0 6|fid:1|integer|0||0 7|name:1|text|0||0 The problem is that I cannot seem to SELECT name:1. How can I do it other than going back and re-aliasing the columns?

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• How to discover table properties from SQLAlchemy mapped object

  - by ssaboum

  Hi, My point is i have a class mapped with a table, in my case in a declarative way, and i want to "discover" table properties, columns, names, relations, from this class : engine = create_engine('sqlite:///' + databasePath, echo=True) # setting up root class for declarative declaration Base = declarative_base(bind=engine) class Ship(Base): __tablename__ = 'ships' id = Column(Integer, primary_key=True) name = Column(String(255)) def __init__(self, name): self.name = name def __repr__(self): return "<Ship('%s')>" % (self.name) So now my goal is from the "Ship" class to get the table columns and their properties from another piece of code. I guess i can deal with it using instrumentation but is there any way provided by the SQLAlchemy API ? Thank you.

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• Is there a library / tool to query MySQL data files (MyISAM / InnoDB) without the server? (the SQLit

  - by MGW

  Oftentimes I want to query my MySQL data directly without a server running or without having access to the server (but having read / write rights to the files). Is there a tool or maybe even a library around to query MySQL data files like it is possible with SQLite? I'm specifically looking for InnoDB and MyISAM support. Performance is not a factor. I don't have any knowledge about MySQL internals, but I presume it should be possible to do and not too hard to get the specific code out? Thank you for any suggestions!

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• How to correctly do SQL UPDATE with weighted subselect?

  - by luminarious

  I am probably trying to accomplish too much in a single query, but have I an sqlite database with badly formatted recipes. This returns a sorted list of recipes with relevance added: SELECT *, sum(relevance) FROM ( SELECT *,1 AS relevance FROM recipes WHERE ingredients LIKE '%milk%' UNION ALL SELECT *,1 AS relevance FROM recipes WHERE ingredients LIKE '%flour%' UNION ALL SELECT *,1 AS relevance FROM recipes WHERE ingredients LIKE '%sugar%' ) results GROUP BY recipeID ORDER BY sum(relevance) DESC; But I'm now stuck with a special case where I need to write the relevance value to a field on the same row as the recipe. I figured something along these lines: UPDATE recipes SET relevance=(SELECT sum(relevance) ...) But I have not been able to get this working yet. I will keep trying, but meanwhile please let me know how you would approach this?

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• How do I get the CoreData Debug argument to output to the console?

  - by radesix

  According to Apple documentation on debugging Core Data it says we should be able to pass an argument to the application which will output the SQL core data sends to SQLite. I have gone into the arguments tab of my executable in XCode and specified the argument: -com.apple.CoreData.SQLDebug 1 However, I see no SQL in the console. I then tried to use this parameter in the CoreDataBooks application provided by Apple just in case there was some other issue in MY program. Even in Apple's example I get no SQL output in the console. Am I doing something wrong? Is Apple's documentation wrong? Should I be looking someplace other than the console? Has anyone else had success with this argument?

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• How to add user customized data to database?

  - by CSharperWithJava

  I am trying to design a sqlite database that will store notes. Each of these notes will have common fields like title, due date, details, priority, and completed. In addition though, I would like to add data for more specialized notes like price for shopping list items and author/publisher data for books. I also want to have a few general purpose fields that users can fill with whatever text data they want. How can I design my database table in this case? I could just have a field for each piece of data for every note, but that would waste a lot of fields and I'd like to have other options and suggestions.

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• Notepad Tutorial: deleteDatabase() function

  - by FelixA

  Hello I have a short question to the notepad tutorial on the android website. I wrote a simple function in the tutorial code to delete the whole database. It looks like this: DataHelper.java public void deleteDatabase() { this.mDb.delete(DATABASE_NAME, null, null); } Notepadv1.java @Override public boolean onCreateOptionsMenu(Menu menu) { boolean result = super.onCreateOptionsMenu(menu); menu.add(0, DELETE_ID, 0, "Delete whole Database"); return result; } @Override public boolean onOptionsItemSelected(MenuItem item) { switch (item.getItemId()) { case DELETE_ID: mDbHelper.deleteDatabase(); return true; } return super.onOptionsItemSelected(item); } But when I run the app and try to delete the database I will get this error in LogCat: sqlite returned: error code = 1, msg= no such table: data Can you help how to fix this problem. It seems that the function deleteDatabase can not reach the database. Thank you very much. Felix

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• Help with optimising SQL query

  - by user566013

  Hi i need some help with this problem. I am working web application and for database i am using sqlite. Can someone help me with one query from databse which must be optimized == fast =) I have table x: ID | ID_DISH | ID_INGREDIENT 1 | 1 | 2 2 | 1 | 3 3 | 1 | 8 4 | 1 | 12 5 | 2 | 13 6 | 2 | 5 7 | 2 | 3 8 | 3 | 5 9 | 3 | 8 10| 3 | 2 .... ID_DISH is id of different dishes, ID_INGREDIENT is ingredient which dish is made of: so in my case dish with id 1 is made with ingredients with ids 2,3 In this table a have more then 15000 rows and my question is: i need query which will fetch rows where i can find ids of dishes ordered by count of ingreedients ASC which i haven added to my algoritem. examle: foo(2,4) will rows in this order: ID_DISH | count(stillMissing) 10 | 2 1 | 3 Dish with id 10 has ingredients with id 2 and 4 and hasn't got 2 more, then is

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• Is this SQL select code following good practice?

  - by acidzombie24

  I am using sqlite and will port to mysql (5) later. I wanted to know if I am doing something I shouldnt be doing. I tried purposely to design so I'll compare to 0 instead of 1 (I changed hasApproved to NotApproved to do this, not a big deal and I haven't written any code). I was told I never need to write a subquery but I do here. My Votes table is just id, ip, postid (I don't think I can write that subquery as a join instead?) and that's pretty much all that is on my mind. Naming conventions I don't really care about since the tables are created via reflection and is all over the place. select id, name, body, upvotes, downvotes, (select 1 from UpVotes where IPAddr=? AND post=Post.id) as myup, (select 1 from DownVotes where IPAddr=@0 AND post=Post.id) as mydown from Post where flag = '0' limit ?, ?"

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• Python/Sqlite app for web or desktop?

  - by ChrisC

  I am in the planning stages of rewriting an Access db I wrote several years ago in a full fledged program. I have very slight experience coding, but not enough to call myself a programmer by far. I'll definitely be learning as I go, so I'd like to keep everything as simple as possible. I've decided on Python and SQLite for my program, but I need help on my next decision. Here is my situation 1) It'll be a desktop program, run locally on each machine, all Windows 2) I want a nice looking GUI with colors, different shaped buttons, nice menus, lists, etc, etc 3) I'm thinking about using a browser interface because (a) from what I've read, browser apps can look really great, and (b) I understand there are lots of free tools to assist in setting up the GUI/GUI code with drag and drop tools, so that helps my "keep it simple" goal. 4) I want the program to be totally portable so it runs completely from one single folder on a user's PC. If I do go the browser app router, a major concern I have is the possibility that a user's browser settings could affect or break the app. How likely is this? What other pros and cons are there for my situation?

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• Getting records from a table based on a filter field and Between but also having the OR login for mu

  - by Pentium10

  I have a this table, where I store multiple ids and an age range (def1,def2) CREATE TABLE "template_requirements" ("_id" INTEGER NOT NULL, "templateid" INTEGER, "def1" VARCHAR(255), "def2" VARCHAR(255), PRIMARY KEY("_id")) Having values such as: templateid | def1 | def2 100 | 7 | 25 200 | 40 | 90 300 | 7 | 25 300 | 40 | 60 as you see for templateid 300 we have an or logic: age between 7 and 25 or age between 40 and 60. I want to get all the template ids that are not for a certain age like 25... What's the problem? If I run a query like this one: SELECT group_concat(templateid) FROM template_requirements where and '25' not between cast(def1 as integer) and cast(def2 as integer) it returns 200, 300, which is wrong, as the 300 matched on row 40 to 60, but shouldn't be included in the result as we have a condition with same templateid 7 to 25 that fails the not beetween stuff. How would be the correct query in SQLite, I would like to keep the group_concat stuff.

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• Efficient way to access a mapping of identifiers in Python

  - by sixbelo

  I am writing an app to do a file conversion and part of that is replacing old account numbers with a new account numbers. Right now I have a CSV file mapping the old and new account numbers with around 30K records. I read this in and store it as dict and when writing the new file grab the new account from the dict by key. My question is what is the best way to do this if the CSV file increases to 100K+ records? Would it be more efficient to convert the account mappings from a CSV to a sqlite database rather than storing them as a dict in memory?

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• iPhone SDK: Data Synchronization

  - by buzzappsoftware

  I am looking for an overview of data synchronization techniques available on the iPhone platform. We need the ability to be able to sync a subset of content from a server to a local database residing on the iPhone. On other projects I have worked on, the data synchronization was handled by the database. Is that available in SQLite? If not, any suggestions on techniques? Rolling our own would not be my first choice. Thanks in advance.

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• When is BIG, big enough for a database?

  - by David ???

  I'm developing a Java application that has performance at its core. I have a list of some 40,000 "final" objects, i.e., I have an initialization input data of 40,000 vectors. This data is unchanged throughout the program's run. I am always preforming lookups against a single ID property to retrieve the proper vectors. Currently I am using a HashMap over a sub-sample of a 1,000 vectors, but I'm not sure it will scale to production. When is BIG, actually big enough for a use of DB? One more thing, an SQLite DB is a viable option as no concurrency is involved, so I guess the "threshold" for db use, is perhaps lower.

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• Programmatically set browser cookie (Firefox)

  - by Andrew

  I know from this question that Firefox 3.0 and up stores its cookies in an SQLite database. My question is: can you access this database from other desktop programs in such a way that you could add a cookie? I realize this has security implications. However, I do not want to read them at all. I want to be able to set one cookie if possible. I don't even want to overwrite a cookie. I just want to add it if it isn't there already. This is sort of a personal project I'm working on for fun. This question is mostly language agnostic. I would prefer a solution in C#, but proof of concept in any language will suffice. Extra credit: It would be cool to set the same cookie in Internet Explorer, too

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• Create tables for a dictionary?

  - by heffaklump

  I'm making a dictionary database in SQLite and need some tips. My SQL is a bit rusty ;) Would you consider this good SQL? It's done with Java JDBC. This is for creating the tables. CREATE TABLE word ( id INTEGER, entry STRING, pos STRING ); CREATE TABLE translation ( word_id INTEGER REFERENCES word(id), entry STRING ); And when filling with data i give each word a number (id) and that words translations get the same number as word_id. What would be the best way of pulling out translations for a specific word?

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• Is there a way to update a database when installing/upgrading an app?

  - by Adam

  I have a main application, and a bunch of sub-applications (they are separate apps, which do not appear on the android home dashboard). I was planning on having a SQLite DB which the main app maintains, and get a list of available sub-apps from. Is there a way to update this main database as the user installs the sub-apps? Two alternative I was thinking of include: User installs the sub-apps via the main app, which would then update the DB. Rather than use the DB to find all installed sub-apps, have each sub-app declare a category, and use intents to query for all applications which match that query (is this even possible? if so, advice is welcomed). Thanks!

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• Store multiple XML files in Android

  - by Federico Perez

  I am developing a survey android app so that: Each survey is downloaded from server as XML file. A survey can have multiple versions (new survey, new XML). When a new XML is downloaded it should overwrite its corresponding previous XML. I would like to store the files in a sqlite database. How can I insert my files into the db? Should I use BLOB or store the content of the XML as string? In any case how should I do it?

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• Join multiple consecutive SQLite database dump files into 1 common database? Purpose: Search through ENTIRE Chrome Browsing History

  - by porg

  Google Chrome 's default web browsing history search engine only lets you access the records of the recent 100 days. Nevertheless in your application data, Chrome keeps your entire browsing history in SQLite database files, with the file naming scheme of "History Index YYYY-MM". I am looking for a way to search… …through my entire browsing history, …with sophisticated filters (limit search terms to certain fields such as URL, domain, title, body text; wildcard or regex terms, date ranges). … in … …either some ready-made software. eHistory came close, as it can limit terms to fields, but it lacks wildcards/regexes, and has the same limited time horizon as the default search. Beyond that, I could not find any suited Chrome extension or standalone (Mac) app. …or a command line to join multiple SQLite database files into one database, which I can then query (with the full syntax power). In the spirit of the pseudo code below: Preferred this way: sqlite --targetDatabase ChromeHistoryAll --importFiles /path/to/ChromeAppData/History\ Index* --importOnlyYetUnknownFiles Or if my desired feature --importOnlyYetUnknownFiles is not possible (feature could also be called "avoid duplicate imports by checking UIDs"), then by explicitly only importing files, of which I know, that they have yet not been imported into the ChromeHistoryAll database: cd ChromeAppData; sqlite --databaseTarget ChromeHistoryAll --importFiles YetNotImported1 YetNotImported2 YetNotImported3 All my queries I would then perform in the database "ChromeHistoryAll" P.S.: Additional question of general interest: Is there a way to perform a database query in a temporary database which was created on-the-fly from multiple files? Like: sqlite --query="SQL query" --targetDatabase DbAll --DBtemporaryInRAM --importFiles db1 db2 db3 This is surely not applicable for my Chrome question, as these History Index files have a combined file size of 500MB together, thus such a query would be of bad performance. But it could come handy in other situations.

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• Error when creating an image from a UIView

  - by Raphael Pinto

  Hi, I'm creating an image from a view whith the folowing code : UIGraphicsBeginImageContext(myView.bounds.size); [myView.layer renderInContext:UIGraphicsGetCurrentContext()]; UIImage *viewImage = UIGraphicsGetImageFromCurrentImageContext(); UIGraphicsEndImageContext(); UIImageWriteToSavedPhotosAlbum(viewImage, nil, nil, nil); The image is created in the user album but in the consol I get this : 2010-05-11 10:17:17.974 myApp[3875:1807] sqlite error 8 [attempt to write a readonly database] 2010-05-11 10:17:18.014 myApp[3875:1807] Backtrace for sqlite error: (0x34e3a909 0x34e3d87f 0x34e3b029 0x34e3b22b 0x34e2f48b 0x34e2dccb 0x34e2d2f7 0x34e2d3bb 0x34e4dcd3 0x34e50515 0x34e51351 0x34e51681 0x34e513f5 0x34e511e3 0x303af57c 0x34e51163 0x303b06e8 0x303ac8e0 0x303ac6d8 0x303ac8c8 0x303aca80 0x30350d55 0x3034a12c) 2010-05-11 10:17:18.077 myApp[3875:1807] sqlite error 8 [attempt to write a readonly database] 2010-05-11 10:17:18.087 myApp[3875:1807] Backtrace for sqlite error: (0x34e3a909 0x34e3b053 0x34e3b22b 0x34e2f48b 0x34e2dccb 0x34e2d2f7 0x34e2d3bb 0x34e4dcd3 0x34e50515 0x34e51351 0x34e51681 0x34e513f5 0x34e511e3 0x303af57c 0x34e51163 0x303b06e8 0x303ac8e0 0x303ac6d8 0x303ac8c8 0x303aca80 0x30350d55 0x3034a12c) 2010-05-11 10:17:18.091 myApp[3875:1807] sqlite error 8 [attempt to write a readonly database] 2010-05-11 10:17:18.095 myApp[3875:1807] Backtrace for sqlite error: (0x34e3a909 0x34e3b085 0x34e3b22b 0x34e2f48b 0x34e2dccb 0x34e2d2f7 0x34e2d3bb 0x34e4dcd3 0x34e50515 0x34e51351 0x34e51681 0x34e513f5 0x34e511e3 0x303af57c 0x34e51163 0x303b06e8 0x303ac8e0 0x303ac6d8 0x303ac8c8 0x303aca80 0x30350d55 0x3034a12c) 2010-05-11 10:17:18.111 myApp[3875:1807] sqlite error 1 [SQL logic error or missing database] 2010-05-11 10:17:18.115 myApp[3875:1807] Backtrace for sqlite error: (0x34e3a909 0x34e3d87f 0x34e3b029 0x34e3b4dd 0x34e2f48b 0x34e2dccb 0x34e2d2f7 0x34e2d3bb 0x34e4dcd3 0x34e50515 0x34e51351 0x34e51681 0x34e513f5 0x34e511e3 0x303af57c 0x34e51163 0x303b06e8 0x303ac8e0 0x303ac6d8 0x303ac8c8 0x303aca80 0x30350d55 0x3034a12c) 2010-05-11 10:17:18.120 myApp[3875:1807] sqlite error 1 [SQL logic error or missing database] 2010-05-11 10:17:18.124 myApp[3875:1807] Backtrace for sqlite error: (0x34e3a909 0x34e3b053 0x34e3b4dd 0x34e2f48b 0x34e2dccb 0x34e2d2f7 0x34e2d3bb 0x34e4dcd3 0x34e50515 0x34e51351 0x34e51681 0x34e513f5 0x34e511e3 0x303af57c 0x34e51163 0x303b06e8 0x303ac8e0 0x303ac6d8 0x303ac8c8 0x303aca80 0x30350d55 0x3034a12c) 2010-05-11 10:17:18.129 myApp[3875:1807] sqlite error 1 [cannot commit - no transaction is active] 2010-05-11 10:17:18.133 myApp[3875:1807] Backtrace for sqlite error: (0x34e3a909 0x34e3b085 0x34e3b4dd 0x34e2f48b 0x34e2dccb 0x34e2d2f7 0x34e2d3bb 0x34e4dcd3 0x34e50515 0x34e51351 0x34e51681 0x34e513f5 0x34e511e3 0x303af57c 0x34e51163 0x303b06e8 0x303ac8e0 0x303ac6d8 0x303ac8c8 0x303aca80 0x30350d55 I don't know where the problem come from. Can you help me?

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• SQLiteQueryBuilder.buildQuery not using selectArgs?

  - by user297468

  Alright, I'm trying to query a sqlite database. I was trying to be good and use the query method of SQLiteDatabase and pass in the values in the selectArgs parameter to ensure everything got properly escaped, but it wouldn't work. I never got any rows returned (no errors, either). I started getting curious about the SQL that this generated so I did some more poking around and found SQLiteQueryBuilder (and apparently Stack Overflow doesn't handle links with parentheses in them well, so I can't link to the anchor for the buildQuery method), which I assume uses the same logic to generate the SQL statement. I did this: SQLiteQueryBuilder builder = new SQLiteQueryBuilder(); builder.setTables(BarcodeDb.Barcodes.TABLE_NAME); String sql = builder.buildQuery(new String[] { BarcodeDb.Barcodes.ID, BarcodeDb.Barcodes.TIMESTAMP, BarcodeDb.Barcodes.TYPE, BarcodeDb.Barcodes.VALUE }, "? = '?' AND ? = '?'", new String[] { BarcodeDb.Barcodes.VALUE, barcode.getValue(), BarcodeDb.Barcodes.TYPE, barcode.getType()}, null, null, null, null); Log.d(tag, "Query is: " + sql); The SQL that gets logged at this point is: SELECT _id, timestamp, type, value FROM barcodes WHERE (? = '?' AND ? = '?') However, here's what the documentation for SQLiteQueryBuilder.buildQuery says about the selectAgs parameter: You may include ?s in selection, which will be replaced by the values from selectionArgs, in order that they appear in the selection. ...but it isn't working. Any ideas?

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