Develop Reference

How do I copy a column from one table to another in SQLite Android? [duplicate]

What is the exact difference between using rawquery and execSQL ??
While writing a query in android activity, when to use rawquery and when to use execSQL ?

From API documentation:
void execSQL (String sql)
Execute a single SQL statement that is NOT a SELECT or any other SQL statement that returns data.
void execSQL (String sql, Object[] bindArgs)
Execute a single SQL statement that is NOT a SELECT/INSERT/UPDATE/DELETE.
The documentation is inconsistent but they behave both the same. Documentation of the latter is more in depth.
Cursor rawQuery (String sql, String[] selectionArgs)
Runs the provided SQL and returns a Cursor over the result set.
Uses for rawQuery are:
You want to query the database with a SELECT statement.
=> rawQuery("SELECT ... returns a set of rows and columns in a Cursor.
It's more efficient to use DatabaseUtils.longForQuery(SQLiteDatabase, String, String[]) or DatabaseUtils.stringForQuery(...) in cases there is only a 1x1 query result, like from SELECT count(*) FROM table (which also has it's own dedicated method: DatabaseUtils.queryNumEntries(...)) - this skips creation of a Cursor object & simplifies code since there is also nothing to close, moveToNext, etc.
Special cases like PRAGMA table_info that returns data in rows (see this question)
Note: Do not use rawQuery for INSERT, UPDATE or DELETE or anything else that modifies the database. You'll run into "Why does a delete rawQuery need a moveToFirst in order to actually delete the rows?". Reason being that queries can defer reading the result until needed (= access to the cursor) which means for SQLite delaying execution of the statement.
Uses for execSQL are:
You have "instructions" for the database. Like CREATE TABLE (or any other CREATE statement, e.g. CREATE INDEX), DROP, PRAGMAs that set properties rather than returning them, ...
INSERT, UPDATE or DELETE when you're not interested in the amount of rows modified or the row id of the last insert.
When you need those, either use the update(), insert(), delete() methods or use a second statement to read those: DatabaseUtils.longForQuery with either SELECT last_insert_rowid() or SELECT changes(). Both return only 1 integer value. (see "Get updated rows count from SQLite in Android using a raw query?" and “SELECT last_insert_rowid()” returns always “0”)
Anything else that relies on executing a statement.

if you want to execute something in database without concerning its output (e.g create/alter tables), then use execSQL, but if you are expecting some results in return against your query (e.g. select records) then use rawQuery

difference between rawquery and execSQL in android sqlite database

What is the exact difference between using rawquery and execSQL ??
While writing a query in android activity, when to use rawquery and when to use execSQL ?

From API documentation:
void execSQL (String sql)
Execute a single SQL statement that is NOT a SELECT or any other SQL statement that returns data.
void execSQL (String sql, Object[] bindArgs)
Execute a single SQL statement that is NOT a SELECT/INSERT/UPDATE/DELETE.
The documentation is inconsistent but they behave both the same. Documentation of the latter is more in depth.
Cursor rawQuery (String sql, String[] selectionArgs)
Runs the provided SQL and returns a Cursor over the result set.
Uses for rawQuery are:
You want to query the database with a SELECT statement.
=> rawQuery("SELECT ... returns a set of rows and columns in a Cursor.
It's more efficient to use DatabaseUtils.longForQuery(SQLiteDatabase, String, String[]) or DatabaseUtils.stringForQuery(...) in cases there is only a 1x1 query result, like from SELECT count(*) FROM table (which also has it's own dedicated method: DatabaseUtils.queryNumEntries(...)) - this skips creation of a Cursor object & simplifies code since there is also nothing to close, moveToNext, etc.
Special cases like PRAGMA table_info that returns data in rows (see this question)
Note: Do not use rawQuery for INSERT, UPDATE or DELETE or anything else that modifies the database. You'll run into "Why does a delete rawQuery need a moveToFirst in order to actually delete the rows?". Reason being that queries can defer reading the result until needed (= access to the cursor) which means for SQLite delaying execution of the statement.
Uses for execSQL are:
You have "instructions" for the database. Like CREATE TABLE (or any other CREATE statement, e.g. CREATE INDEX), DROP, PRAGMAs that set properties rather than returning them, ...
INSERT, UPDATE or DELETE when you're not interested in the amount of rows modified or the row id of the last insert.
When you need those, either use the update(), insert(), delete() methods or use a second statement to read those: DatabaseUtils.longForQuery with either SELECT last_insert_rowid() or SELECT changes(). Both return only 1 integer value. (see "Get updated rows count from SQLite in Android using a raw query?" and “SELECT last_insert_rowid()” returns always “0”)
Anything else that relies on executing a statement.

if you want to execute something in database without concerning its output (e.g create/alter tables), then use execSQL, but if you are expecting some results in return against your query (e.g. select records) then use rawQuery

Android SQLite Insert-Select

There are two different methods for inserting a row into table:
execSql, using it I can execute sql statements with SELECT - INSERT. But it doesn't return id of new row.
different inserts - I can get insert-id here, but I can't create insert queries with substitution values from another table.
I can split my query into two, but isn't it slower, than one query?

Do your insert however you like, then execSql "select last_insert_rowid()".

Android Delete Query

I'm attempting to delete all rows in one table that do not have a corresponding ID in another table. Since apparently SQLite does not support joins in deletes I am trying to do something along these lines:
DELETE FROM my_table WHERE my_id NOT IN (SELECT _id FROM my_table2);
However, I apparently can not use rawQuery since it returns a cursor so I have to use the delete function. I'm having some trouble getting this working. Here is the query I'm trying:
mDb.delete("my_table", "my_id NOT IN ?", new String[]{"(SELECT _id FROM my_table2)"});
Thanks.

You shouldn't use a .rawQuery, as you stated, but you can use .execSQL() to accomplish it. I regularly use it for deletions myself.

I think the only way is to execute your select and dynamically combine your WHERE clause.

You have to use execSQL instead rawQuery because rawQuery is used for the statement that return data and execSQL is used for the statements that don't return data like DELETE

How to return unique rows within a column in Android SQLite?

Really all I want to do is say the query SELECT DISTINCT column FROM table but I can't figure out how to structure it in the enourmous query methods that are part of SQLiteDatabase
I'm just trying to get the names of all contacts in a table.

You seem to know the sql query you want to run. Have you tried using rawQuery()?

You will probably find this version of the SQLiteDatabase#query method most useful.