I would like to do this query in SQLite:
update table1 set col1 = (? || substr (col1, col2))
where table1.id in (select id from table2 where condition);
I'm not sure how to do this. SQLiteDatabase.rawQuery doesn't work. All the other APIs I've seen don't allow the expression in the "set" part. If I could use SQLiteStatement, it would work. But that constructor is only visible in its package, not to my code :(
Ideally, I would do something like this:
String query =
"update Table1 set " +
" col1 = (? || substr (col1, col2)), " +
" col2 = ? " +
"where Table1.id in " +
" (select id from Table2 where col3 = ?)";
String[] args = new String[3];
args[0] = arg0;
args[1] = arg1;
args[2] = arg2;
SQLiteStatement statement = new SQLiteStatement (getDb(), query, args);
int rowsUpdated = 0;
try
{
rowsUpdated = statement.executeUpdateDelete();
} finally {
statement.close();
}
Any ideas? Thanks.
Usually when we want to run CRUD operations we use SQLiteDatabase.execSQL().
SQLiteDatabase.rawQuery() is generally used for select queries and it returns a Cursor with the result set.
Although rawQuery() should theoretically work because according to the docs
Runs the provided SQL and returns a Cursor over the result set.
But others have reported that it doesn't work with update queries, so I'm not entirely sure about that.
Related
So i have been strugglin to get this query to work with GreenDao, and my problem is the start of the query, which (using rawquery) starts after the where clause.
It it even possible to do this query with GreenDao or do i have to use standard SQL Queries accessing the database without using GreenDao?
select count (distinct VISIBLE_PAGE_ID) from HOME_ITEM2 where IS_VISIBLE=1 and IS_ACTIVE = 1
So i was able to do it using just SQL, no idea if there are any BuildIn methods to do the same thing:
String query = "SELECT COUNT (DISTINCT "
+ HomeItem2Dao.Properties.VisiblePageId.columnName+
") from "
+ HomeItem2Dao.TABLENAME
+ " where "
+ HomeItem2Dao.Properties.IsVisible.columnName + " = 1 and "
+ HomeItem2Dao.Properties.IsActive.columnName + " = 1";
Integer count = 0;
Cursor cursor =
MainApplication.getInstance().getDaoSession().getDatabase().rawQuery(
query, null
);
if(cursor.moveToFirst()){
count = cursor.getInt(0);
}
cursor.close();
You can use GreenDao's CountQuery class to execute count(*) queries. while using QueryBuilder use buildCount() method instead of build() method. Example below.
HomeItem2 homeItem2Dao = ((Application) context.getApplicationContext())
.getDaoSession().getHomeItem2Dao();
QueryBuilder<HomeItem2> queryBuilder =
homeItem2Dao.queryBuilder().where(
HomeItem2Dao.Properties.IsVisible.eq(true),
HomeItem2Dao.Properties.IsActive.eq(true));
return queryBuilder.buildCount().count();
I created a pull request with the library adding a function to build a count query with a distinct column expression.
There's actually CountQuery in GreenDao. Take a look at these links:
http://greenrobot.org/files/greendao/javadoc/2.1/de/greenrobot/dao/query/CountQuery.html
http://greendao-orm.com/2012/06/08/greendao-1-2-release/
Hope it helps.
I have tableA, tableB, and tableC
table A and tableB are joined by tableA.Id(PK) = tableB.tableAId(FK)
table B and tableC are joined by tableB.Id(PK) = tableC.tableBId(FK)
I want to be able to do this:
SELECT c.ALL from tableC c
INNER JOIN tableB b on c.tableBId = b.Id
INNER JOIN tableA a on b.tableAId = a.Id
WHERE a.Id = 108
I have found a lot of posts on the web which uses db.rawquery() to implement this query. However I have also heard that rawquery() is less secure than query(). So for the sake of seeking best practice as a beginner, my question is:
Is there a way to implement this query using db.query() instead of db.rawquery()?
thanks in advance.
Is there a way to implement this query using db.query() instead of
db.rawquery()?
So it's worth to say that rawQuery() makes a trick. But also exists another approach.
query() method is designed for performing queries over one table. But the best way how to JOIN tables in SQLite is to use SQLiteQueryBuilder and with setTables() method you are able to join.
Hence i recommend you to use mentioned SQLiteQueryBuilder. But it's little more complicated against rawQuery() method where you need to assign only raw statement.
If don't know how to start, check this example:
How to use a join with SQLite
Note:
Is the fact that rawQuery() is less secure than query() because query() method uses precompiled statements which are safer than "raw" statements. But always you can(should) use placeholders which significantly increase safety of statement as main protection against SQL injections and statement becomes much more human-readable as well.
This is kind of late, but I thought others who're looking for that might benefit from that:
db.query() method natively supports LEFT OUTER JOIN AND INNER JOIN via its table argument so you don't actually need to use SQLiteQueryBuilder to accomplish that. Also it's easier and and pretty much straight forward.
This method is widely used in Google I/O 2015 Schedule app's source code.
A Quick example (String constants left out for brevity):
Cursor cursor = db.query(NoteContract.Note.TABLE_NAME
+ " LEFT OUTER JOIN authors ON notes._id=authors.note_id", projection, selection,
selectionArgs, null, null, "notes._id");
The key is in the first argument to db.query().
Currently, only LEFT OUTER JOIN and INNER JOIN are supported, which is quite sufficient for most apps.
I hope this answer helps others who're looking for this.
Yes you can use query() instead of rawQuery(), given a single assumption - there are no two same column names in the tables you are joining.
If that criteria is fullfilled, then you can use this answer
https://stackoverflow.com/a/34688420/3529903
As per SharpEdge's comment and after trying a more complex example based upon Nimrod Dayan's answer, here's a more complex example.
4 joins are used, a generated column is also used. It uses an expression (subtracts timestamps) and then uses that in the WHERE clause.
Basically, the method is to append the join clauses to the table name string (SQLite then moves this for you to after the columns).
DBConstants.SQL????? is resolved to the respective SQL e.g. DBConstants.SQLISNOTNULL resolves to IS NOT NULL
DBConstans.CALCULATED????? are names for calculated columns.
DB????TableConstants.????_COL resolves to column names (.._FULL resolves to table.column e.g. to avoid ambiguous _ID columns).
The method (getToolRules) is as follows :-
public Cursor getToolRules(boolean rulesexist,
int minimumruleperiodindays,
int minimumbuycount) {
String columns[] = new String[] {
"0 " + DBConstants.SQLAS + DBConstants.STD_ID,
DBProductusageTableConstants.PRODUCTUSAGE_PRODUCTREF_COL,
DBProductusageTableConstants.PRODUCTUSAGE_AISLEREF_COL,
DBProductusageTableConstants.PRODUCTUSAGE_COST_COL,
DBProductusageTableConstants.PRODUCTUSAGE_BUYCOUNT_COL,
DBProductusageTableConstants.PRODUCTUSAGE_FIRSTBUYDATE_COL,
DBProductusageTableConstants.PRODUCTUSAGE_LATESTBUYDATE_COL,
DBProductusageTableConstants.PRODUCTUSAGE_ORDER_COL,
DBProductusageTableConstants.PRODUCTUSAGE_RULESUGGESTFLAG_COL,
DBProductusageTableConstants.PRODUCTUSAGE_CHECKLISTFLAG_COL,
DBProductusageTableConstants.PRODUCTUSAGE_CHECKLISTCOUNT_COL,
"(" +
DBProductusageTableConstants.PRODUCTUSAGE_LATESTBUYDATE_COL +
"- " +
DBProductusageTableConstants.PRODUCTUSAGE_FIRSTBUYDATE_COL +
" / (86400000)" +
") " + DBConstants.SQLAS + DBConstants.CALCULATED_RULEPERIODINDAYS,
DBProductsTableConstants.PRODUCTS_NAME_COL,
DBAislesTableConstants.AISLES_NAME_COL,
DBAislesTableConstants.AISLES_ORDER_COL,
DBAislesTableConstants.AISLES_SHOPREF_COL,
DBShopsTableConstants.SHOPS_NAME_COL,
DBShopsTableConstants.SHOPS_CITY_COL,
DBShopsTableConstants.SHOPS_ORDER_COL,
DBRulesTableConstants.RULES_ID_COL_FULL +
DBConstants.SQLAS + DBRulesTableConstants.RULES_ALTID_COL,
DBRulesTableConstants.RULES_AISLEREF_COL,
DBRulesTableConstants.RULES_PRODUCTREF_COL,
DBRulesTableConstants.RULES_NAME_COL,
DBRulesTableConstants.RULES_USES_COL,
DBRulesTableConstants.RULES_PROMPT_COL,
DBRulesTableConstants.RULES_ACTON_COL,
DBRulesTableConstants.RULES_PERIOD_COL,
DBRulesTableConstants.RULES_MULTIPLIER_COL
};
String joinclauses = DBConstants.SQLLEFTJOIN +
DBProductsTableConstants.PRODUCTS_TABLE +
DBConstants.SQLON +
DBProductusageTableConstants.PRODUCTUSAGE_PRODUCTREF_COL + " = " +
DBProductsTableConstants.PRODUCTS_ID_COL_FULL + " " +
DBConstants.SQLLEFTJOIN +
DBAislesTableConstants.AISLES_TABLE +
DBConstants.SQLON +
DBProductusageTableConstants.PRODUCTUSAGE_AISLEREF_COL + " = " +
DBAislesTableConstants.AISLES_ID_COL_FULL +
DBConstants.SQLLEFTJOIN +
DBShopsTableConstants.SHOPS_TABLE +
DBConstants.SQLON +
DBAislesTableConstants.AISLES_SHOPREF_COL + " = " +
DBShopsTableConstants.SHOPS_ID_COL_FULL +
DBConstants.SQLLEFTJOIN +
DBRulesTableConstants.RULES_TABLE +
DBConstants.SQLON +
DBProductusageTableConstants.PRODUCTUSAGE_PRODUCTREF_COL + " = " +
DBRulesTableConstants.RULES_PRODUCTREF_COL +
DBConstants.SQLAND +
DBProductusageTableConstants.PRODUCTUSAGE_AISLEREF_COL + " = " +
DBRulesTableConstants.RULES_AISLEREF_COL
;
String ruleexistoption = DBRulesTableConstants.RULES_ID_COL_FULL;
if (rulesexist) {
ruleexistoption = ruleexistoption + DBConstants.SQLISNOTNULL;
} else {
ruleexistoption = ruleexistoption + DBConstants.SQLISNULL;
}
String whereclause = DBProductusageTableConstants.PRODUCTUSAGE_BUYCOUNT_COL +
" = ?" +
DBConstants.SQLAND + ruleexistoption +
DBConstants.SQLAND +
"(" + DBConstants.CALCULATED_RULEPERIODINDAYS + " / ?) > 0" +
DBConstants.SQLAND +
DBProductusageTableConstants.PRODUCTUSAGE_BUYCOUNT_COL + " > ?";
if (minimumbuycount > 0) {
--minimumbuycount;
}
String[] whereargs = new String[] {
"0",
Integer.toString(minimumruleperiodindays),
Integer.toString(minimumbuycount)
};
return db.query(DBProductusageTableConstants.PRODUCTUSAGE_TABLE + joinclauses,
columns,whereclause,whereargs,null,null,null);
}
The base SQL, which was created in SQLite Manager, used as a guide to building the method (looks far nicer, IMHO, than the SQL extracted from the cursor in debug) is :-
Note! 0 AS _ID is used to enable the cursor to be used by a CursorAdapter (i.e. CursorAdapters require a column named _ID)
SELECT
0 AS _id,
productusage.productusageproductref,
productusage.productusageaisleref,
productusage.productusageorder,
productusage.productusagecost,
productusage.productusagebuycount,
productusage.productusagefirstbuydate,
productusage.productusagelatestbuydate,
productusage.productusagerulesuggestflag,
productusage.productusagechecklistflag,
productusage.productusagechecklistcount,
/*********************************************************************************************************************************
Calculate the period in days from between the firstbuydate and the latestbuydate
*********************************************************************************************************************************/
(productusagelatestbuydate - productusagefirstbuydate) / (1000 * 60 * 60 * 24) AS periodindays,
products.productname,
aisles.aislename,
aisles.aisleorder,
aisles.aisleshopref,
shops.shopname,
shops.shopcity,
shops.shoporder,
rules._id AS rule_id,
rules.rulename,
rules.ruleuses,
rules.ruleprompt,
rules.ruleacton,
rules.ruleperiod,
rules.rulemultiplier
FROM productusage
LEFT JOIN products ON productusageproductref = products._id
LEFT JOIN aisles ON productusageaisleref = aisles._id
LEFT JOIN shops ON aisles.aisleshopref = shops._id
LEFT JOIN rules ON productusageaisleref = rules.ruleaisleref AND productusageproductref = rules.ruleproductref
WHERE productusagebuycount > 0 AND rules._id IS NULL AND (periodindays / 2) > 0 AND productusage.productusagebuycount > 0
public HashMap<String, String> get_update_invoice_getdata(String gen) {
// TODO Auto-generated method stub
HashMap<String, String> wordList;
wordList = new HashMap<String, String>();
Cursor cur_1 = ourDataBase
.rawQuery(
"SELECT * FROM Invoice i JOIN Client c ON i.Client_id=c.Client_id JOIN TAX t ON i.Tax_id=t.Tax_id JOIN Task it ON i.Task_id=it.Task_id WHERE i.Inv_no=?",
new String[] { gen });
int intext = cur_1.getColumnIndex(C_ORG_NAME);
int intext5 = cur_1.getColumnIndex(TA_NAME);
int intext6 = cur_1.getColumnIndex(TA_RATE);
int intext7 = cur_1.getColumnIndex(TA_QTY);
int intext8 = cur_1.getColumnIndex(TA_TOTAL);
if (cur_1.moveToFirst()) {
do {
wordList.put("Org_name", cur_1.getString(intext));
wordList.put("client_id", cur_1.getString(2));
wordList.put("po_number", cur_1.getString(4));
wordList.put("date", cur_1.getString(3));
wordList.put("dis_per", cur_1.getString(7));
wordList.put("item_name", cur_1.getString(intext5));
wordList.put("item_rate", cur_1.getString(intext6));
wordList.put("item_cost", cur_1.getString(intext7));
wordList.put("item_total", cur_1.getString(intext8));
} while (cur_1.moveToNext());
}
return wordList;
}
android noob... I have two tables, with a one to many relationship between country_tbl and city_tbl, and I would like to concatenate values from city_tbl.landmark_col with GROUP_CONCAT() and INSERT all the landmark_col values as a single String into country_tbl.all_landmarks column. The SQL seems to require a nested SELECT to concatenate the landmark_col values before passing them to the country_tbl... something like:
UPDATE country_tbl
SET country_tbl.all_landmarks = (SELECT landmarks_col FROM
(SELECT country_id, group_concat(landmarks_col)
FROM city_tbl INNER JOIN country_tbl
ON country_tbl.country_id = city_tbl.country_id
GROUP BY country_tbl.country_id)
AS country_landmarks
WHERE country_tbl.country_id = country_landmarks.country_id)
WHERE
EXISTS (
SELECT *
FROM country_landmarks
WHERE country_tbl.country_id = country_landmarks.country_id
);
Not sure if nested select statements are even supported or if just too resource intensive... there must be a better way, as it seems like using rawQuery is not the best solution. Not sure if I should be creating temporary tables, using ContentProviders, or passing a cursor...?
I answered this by splitting up the long SQL query into two parts. First I created a subquery with a SQLiteQueryBuilder and ran using rawQuery to get a two column cursor with the location_id and the group_concat values for the landmark_names. I was then able to cycle through the cursor to update the country table with each of the appropriate concatenated values of all the landmark names for that country.
The query below is a tad more complicated than the question above (which I simplified before posting), only because I had to join a landmarks list table with another landmark_type table by the landmark_type_id, and my real goals was to concatenate the shorter list of landmark_type by country, not the long list of all the landmark_names by country. Anyway, it works.
public void UpdateCountryLandmarks() throws SQLException {
Cursor c = null;
String subquery = SQLiteQueryBuilder.buildQueryString(
// include distinct
true,
// FROM tables
LANDMARK_TYPE_TABLE + "," + LANDMARKS_TABLE,
// two columns (one of which is a group_concat()
new String[] { LANDMARKS_TABLE + "." + LOCATION_ID + ", group_concat(" + LANDMARK_TYPE_TABLE + "." + LANDMARK_TYPE + ",\", \") AS " + LANDMARK_NAMES },
// where
LANDMARK_TYPE_TABLE + "." + LANDMARK_ID + "=" + LANDMARKS_TABLE + "." + LANDMARK_TYPE_ID,
// group by
LANDMARKS_TABLE + "." + LOCATION_ID, null, null, null);
c = mDb.rawQuery(subquery, null);
if (c.moveToFirst()) {
do {
String locationId = c.getString(c.getColumnIndex(LOCATION_ID));
String landmarkNames = c.getString(c.getColumnIndex(LANDMARK_NAMES));
ContentValues cv = new ContentValues();
cv.put(LANDMARK_NAMES, landmarkNames);
mDb.update(COUNTRY_TABLE, cv, LOCATION_ID + "=" + locationId, null);
} while (c.moveToNext());
}
c.close();
}
Supposing I have this sqlite database structure:
ID PRODUCT_NAME AVAILABILITY
1 foo 0
2 bar 1
3 baz 0
4 faz 1
How cand I modify the value of the AVAILABILITY fom 1 -> 0 where PRODUCT_NAME = 'bar' ?
Something like this,
Pseudocod:
db.execSQL( "UPDATE TABLE" + Table_name + "MODIFY" + availability + "=" + 0 + "WHERE" + product_name + "like ? " + 'bar');
I assume that I also have to drop and recreate table using onCreate() and onUpgrade() methods, right?
Some code will be highly appreciated.
Use this:
SQLiteDatabase db=dbHelper.getWritableDatabase();
String sql="update "+Table_name+" set availability='0' where product_name like 'bar'";
Object[] bindArgs={"bar"};
try{
db.execSQL(sql, bindArgs);
return true;
}catch(SQLException ex){
Log.d(tag,"update data failure");
return false;
}
You want update not alter. alter is for the database schema, update is for the data stored in it.
For example:
update TABLE_NAME set AVAILABILITY = 0 where PRODUCT_NAME like 'bar';
Also, do not just stick strings together to build an sql query. Use a prepared statement or other statement building library to avoid SQL injection attacks and errors.
You could also use the update(), insert(), query(), delete() methods that Android gives you
// define the new value you want
ContentValues newValues = new ContentValues();
newValues.put("AVAILABILITY", 0);
// you can .put() even more here if you want to update more than 1 row
// define the WHERE clause w/o the WHERE and replace variables by ?
// Note: there are no ' ' around ? - they are added automatically
String whereClause = "PRODUCT_NAME == ?";
// now define what those ? should be
String[] whereArgs = new String[] {
// in order the ? appear
"bar"
};
int amountOfUpdatedColumns = db.update("YourTableName", newValues, whereClause, whereArgs);
The advantage here is that you get correct SQL syntax for free. It also escapes your variables which prevents bad things to happen when you use "hax ' DROP TABLE '" as argument for ?.
The only thing that is still not safe is using column LIKE ? with arguments like "hello%world_" because % (match anything of several chars) and _ (match any 1 char) are not escaped.
You would need to escape those manually (e.g. place a ! before each _ or %) and use
String whereClause = "LIKE ? ESCAPE '!'"
String[] whereArgs = new String[] {
likeEscape("bar")
// likeEscape could be replaceAll("!", "!!").replaceAll("%", "!%").replaceAll("_", "!_") maybe
}
Btw: your single code line should work if you use
db.execSQL( "UPDATE " + Table_name + " SET " + availability + "=0 WHERE " + product_name + " like 'bar'");
SqlLite uses "SQL". You need a SQL "update"
db.execSQL( "update mytable set availability=0 where product_name like '%" + bar + "%'");
Here's a good link for SQL "select", "update", "insert" and "delete" ("CRUD") commands:
http://www.w3schools.com/sql/default.asp
Background
I have an Android project that has a database with two tables: tbl_question and tbl_alternative.
To populate the views with questions and alternatives I am using cursors. There are no problems in getting the data I need until I try to join the two tables.
Tbl_question
-------------
_id
question
categoryid
Tbl_alternative
---------------
_id
questionid
categoryid
alternative
I want something like the following:
SELECT tbl_question.question, tbl_alternative.alternative where
categoryid=tbl_alternative.categoryid AND tbl_question._id =
tbl_alternative.questionid.`
This is my attempt:
public Cursor getAlternative(long categoryid) {
String[] columns = new String[] { KEY_Q_ID, KEY_IMAGE, KEY_QUESTION, KEY_ALT, KEY_QID};
String whereClause = KEY_CATEGORYID + "=" + categoryid +" AND "+ KEY_Q_ID +"="+ KEY_QID;
Cursor cursor = mDb.query(true, DBTABLE_QUESTION + " INNER JOIN "+ DBTABLE_ALTERNATIVE, columns, whereClause, null, null, null, null, null);
if (cursor != null) {
cursor.moveToFirst();
}
return cursor;
I find this way to form queries harder than regular SQL, but have gotten the advice to use this way since it is less error prone.
Question
How do I join two SQLite tables in my application?
You need rawQuery method.
Example:
private final String MY_QUERY = "SELECT * FROM table_a a INNER JOIN table_b b ON a.id=b.other_id WHERE b.property_id=?";
db.rawQuery(MY_QUERY, new String[]{String.valueOf(propertyId)});
Use ? bindings instead of putting values into raw sql query.
An alternate way is to construct a view which is then queried just like a table.
In many database managers using a view can result in better performance.
CREATE VIEW xyz SELECT q.question, a.alternative
FROM tbl_question AS q, tbl_alternative AS a
WHERE q.categoryid = a.categoryid
AND q._id = a.questionid;
This is from memory so there may be some syntactic issues.
http://www.sqlite.org/lang_createview.html
I mention this approach because then you can use SQLiteQueryBuilder with the view as you implied that it was preferred.
In addition to #pawelzieba's answer, which definitely is correct, to join two tables, while you can use an INNER JOIN like this
SELECT * FROM expense INNER JOIN refuel
ON exp_id = expense_id
WHERE refuel_id = 1
via raw query like this -
String rawQuery = "SELECT * FROM " + RefuelTable.TABLE_NAME + " INNER JOIN " + ExpenseTable.TABLE_NAME
+ " ON " + RefuelTable.EXP_ID + " = " + ExpenseTable.ID
+ " WHERE " + RefuelTable.ID + " = " + id;
Cursor c = db.rawQuery(
rawQuery,
null
);
because of SQLite's backward compatible support of the primitive way of querying, we turn that command into this -
SELECT *
FROM expense, refuel
WHERE exp_id = expense_id AND refuel_id = 1
and hence be able to take advanatage of the SQLiteDatabase.query() helper method
Cursor c = db.query(
RefuelTable.TABLE_NAME + " , " + ExpenseTable.TABLE_NAME,
Utils.concat(RefuelTable.PROJECTION, ExpenseTable.PROJECTION),
RefuelTable.EXP_ID + " = " + ExpenseTable.ID + " AND " + RefuelTable.ID + " = " + id,
null,
null,
null,
null
);
For a detailed blog post check this
http://blog.championswimmer.in/2015/12/doing-a-table-join-in-android-without-using-rawquery
"Ambiguous column" usually means that the same column name appears in at least two tables; the database engine can't tell which one you want. Use full table names or table aliases to remove the ambiguity.
Here's an example I happened to have in my editor. It's from someone else's problem, but should make sense anyway.
select P.*
from product_has_image P
inner join highest_priority_images H
on (H.id_product = P.id_product and H.priority = p.priority)