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()".
Related
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
In my Android SQLite databese query I have an INSERT INTO statement followed by about 600 ('data1'),('data2')... tags, generated by code.
After db.exec(sql) I got this error: "too many terms in compound SELECT (code1); while compiling INSERT INTO.. "
Is there any way to increase this limitation?
The limit SQLITE_MAX_COMPOUND_SELECT cannot be raised at runtime,
So you need to split your inserts into batches of 500 rows each. This will be more efficient than inserting one row per query. For e.g.
BEGIN TRANSACTION
INSERT INTO tablename (data1,data2) VALUES ("data1","data2")
INSERT INTO tablename (data1,data2) VALUES ("data1","data2")
INSERT INTO tablename (data1,data2) VALUES ("data1","data2")
...
END TRANSACTION
Also see Insert Multiple Rows in SQLite
I wanna insert some row to a table in Android, I'm using this:
INSERT INTO MyTable (Column_1, Column_1) VALUES ('X',100);
The query runs and no exception is thrown, but when I retrieve all rows from MyTable, no row
is returned.
I do not want to use the insert method, because the queries are read from a file and I want to insert them to the database.
What's wrong with my code?
Update : The rawQuery() method doesn't run the query, but execSQL() does.
The title of your question suggests you're using rawQuery(). It just compiles the SQL but does not run it. Calling one of the moveTo...() methods on the returned Cursor would also execute the SQL.
For an insert query, use execSQL() instead of rawQuery(), even if the documentation incorrectly states it should not be used with INSERT.
How is your Table organized?
You seem to use twice the same column Column_1 is this a typo?
Alternative, you could use insert-command of SQListeDatabase insteat:
http://developer.android.com/reference/android/database/sqlite/SQLiteDatabase.html#insert%28java.lang.String,%20java.lang.String,%20android.content.ContentValues%29
I have a database and I want to sort it. I came across several code that selects a sorted data but does not modify the database in itself.
I came across..
So how do I sort a database?
You don't sort tables in relational database.
You create index on them. And use ORDER BY in your query. That way your query result will be sorted.
When creating database create index on column to have better query performance:
CREATE INDEX sorted_idx ON table_name(indexed_column ASC);
more about indexes:
http://www.sqlite.org/lang_createindex.html
Then in code select using ORDER BY
db.rawQuery("SELECT * FROM table_name ORDER BY indexed_column ASC", null);
If you mean by 'sort a database' to simple sort a table,
Create temp table as sorted select, eg you have unsorted table1 a you want to sort it by column1 then do this:
CREATE TABLE temp_table1
AS SELECT *
FROM table1
ORDER BY column1;
Drop the original table.
Rename temp_table1 to table1.
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