I have an appcelerator titanium project (you don't need to be familiar with the platform to help me) that I am using to create an iOS app. I want to have a database with a table that is filled with several rows for the first time, and then left alone after the first time.
I know you can create a table if it doesn't exist. Is there something similar for Inserting data?
Thanks!
Expanding on MPelletier's response with some Titanium-specific code, you could do the following in your project:
var my_db = Ti.Database.open('nameofdb');
var my_result_set = my_db.execute('SELECT * FROM MyTable');
var records = my_result_set.rowCount;
The records variable will indicate whether or not you have data in your table and then you can act accordingly.
There are a couple of nice ORM-ish utilities out there for Titanium: TiStore and Joli are the two I've used. Both are inspired by ActiveRecord and can be helpful in reducing your DB-related code. They're on Github if you want to know more about them!
There's INSERT OR REPLACE if you want, but you might as well just check against the number of rows on the table:
SELECT COUNT(*) FROM MyTable;
Then decide to enter them on that.
You can create your DB and insert data in it via SQLLiteManager or whatever tool you want and then dump it.
Take the file you dumped, put it in your Titanium project folder (somewhere in the Resources folder).
Then this line of code will take the content of the .sqlite file and insert it in the iOS db:
var db = Ti.Database.install('../your-db.sqlite', 'your-db-name');
Just don't forget the CREATE IF NOT EXISTS statement in your SQL file.
Or use REPLACE instead of INSERT as MPelletier said.
Related
I have an Ionic App using SQLite. I don't have any problems with implementation.
The issue is that I need to import an SQL file using SQLitePorter to populate the database with configuration info.
But also, on the same database I have user info, so my question is:
Everytime I start the app, it will import the sql file, fill the database and probably overwrite my user data too? Since it is all on the same base?
I assume that you can always init your table using string queries inside your code. The problem is not that you are importing a .sql file. Right?
According to https://www.sqlitetutorial.net/sqlite-create-table/ it is obvious that you always create a table with [IF NOT EXISTS] switch. Writing a query like :
CREATE TABLE [IF NOT EXISTS] [schema_name].table_name (
column_1 data_type PRIMARY KEY);
you let sqlite to decide if it's going to create a table with the risk to overwrite an existing table. It is supposed that you can trust that sqlite is smart enough, not to overwrite any information especially if you use 'BEGIN TRANSACTION' - 'COMMIT' procedure.
I give my answer assuming that you have imported data and user data in distinct tables, so you can manipulate what you populate and what you don't. Is that right?
What I usually do, is to have a sql file like this:
DROP TABLE configutation_a;
DROP TABLE configutation_b;
CREATE TABLE configutation_a;
INSERT INTO configutation_a (...);
CREATE TABLE configutation_b;
INSERT INTO configutation_b (...);
CREATE TABLE IF NOT EXIST user_data (...);
This means that every time the app starts, I am updating with the configuration data I have at that time (that's is why we use http.get to get any configuration file from a remote repo in the future) and create user data only if user_data table is not there (hopefully initial start).
Conclusion: It's always a good practice, in my opinion, to trust a database product 100% and abstractly let it do any transaction that might give you some risk if you implemented your self in your code; since it gives a tool for that.For example, the keyword [if not exists], is always safer than implementing a table checker your self.
I hope that helps.
PS: In case you refer in create database procedure, SQLite, connects to a database file and it doesn't exist, it creates it. For someone comfortable in sqlite command line, when you type
sqlite3 /home/user/db/configuration.db will connect you with this db and if the file is not there, it will create it.
The only thing I don't have an automated tool for when working with Oracle is a program that can create INSERT INTO scripts.
I don't desperately need it so I'm not going to spend money on it. I'm just wondering if there is anything out there that can be used to generate INSERT INTO scripts given an existing database without spending lots of money.
I've searched through Oracle with no luck in finding such a feature.
It exists in PL/SQL Developer, but errors for BLOB fields.
Oracle's free SQL Developer will do this:
http://www.oracle.com/technetwork/developer-tools/sql-developer/overview/index.html
You just find your table, right-click on it and choose Export Data->Insert
This will give you a file with your insert statements. You can also export the data in SQL Loader format as well.
You can do that in PL/SQL Developer v10.
1. Click on Table that you want to generate script for.
2. Click Export data.
3. Check if table is selected that you want to export data for.
4. Click on SQL inserts tab.
5. Add where clause if you don't need the whole table.
6. Select file where you will find your SQL script.
7. Click export.
Use a SQL function (I'm the author):
https://github.com/teopost/oracle-scripts/blob/master/fn_gen_inserts.sql
Usage:
select fn_gen_inserts('select * from tablename', 'p_new_owner_name', 'p_new_table_name')
from dual;
where:
p_sql – dynamic query which will be used to export metadata rows
p_new_owner_name – owner name which will be used for generated INSERT
p_new_table_name – table name which will be used for generated INSERT
p_sql in this sample is 'select * from tablename'
You can find original source code here:
http://dbaora.com/oracle-generate-rows-as-insert-statements-from-table-view-using-plsql/
Ashish Kumar's script generates individually usable insert statements instead of a SQL block, but supports fewer datatypes.
I have been searching for a solution for this and found it today. Here is how you can do it.
Open Oracle SQL Developer Query Builder
Run the query
Right click on result set and export
http://i.stack.imgur.com/lJp9P.png
You might execute something like this in the database:
select "insert into targettable(field1, field2, ...) values(" || field1 || ", " || field2 || ... || ");"
from targettable;
Something more sophisticated is here.
If you have an empty table the Export method won't work. As a workaround. I used the Table View of Oracle SQL Developer. and clicked on Columns. Sorted by Nullable so NO was on top. And then selected these non nullable values using shift + select for the range.
This allowed me to do one base insert. So that Export could prepare a proper all columns insert.
If you have to load a lot of data into tables on a regular basis, check out SQL Loader or external tables. Should be much faster than individual Inserts.
You can also use MyGeneration (free tool) to write your own sql generated scripts. There is a "insert into" script for SQL Server included in MyGeneration, which can be easily changed to run under Oracle.
I want a debug function to do this, but I'm unaware of whether one already exists. Going through and using 'drop table' for each of my tables will be a pain.
Help appreciated.
Since the database is just one file, you can indeed just erase it. If you want something more automatic, you can use the following to do it all programmatically:
Recover your schema:
SELECT group_concat(sql,';') FROM sqlite_master;
Disconnect from the database
Delete the database file
Create your schema again with what was returned from the above query
If you used any particular options for your original database (page_size, etc), they will have to be declared manually as well.
to "drop database" for sqlite, simply delete the database file (and recreate if needed)
I need to modify a column in a SQLite database but I have to do it programatically due to the database already being in production. From my research I have found that in order to do this I must do the following.
Create a new table with new schema
Copy data from old table to new table
Drop old table
Rename new table to old tables name
That seems like a ridiculous amount of work for something that should be relatively easy. Is there not an easier way? All I need to do is change a constraint on a existing column and give it a default value.
That's one of the better-known drawbacks of SQLite (no MODIFY COLUMN support on ALTER TABLE), but it's on the list of SQL features that SQLite does not implement.
edit: Removed bit that mentioned it may being supported in a future release as the page was updated to indicate that is no longer the case
If the modification is not too big (e.g. change the length of a varchar), you can dump the db, manually edit the database definition and import it back again:
echo '.dump' | sqlite3 test.db > test.dump
then open the file with a text editor, search for the definition you want to modify and then:
cat test.dump | sqlite3 new-test.db
As said here, these kind of features are not implemented by SQLite.
As a side note, you could make your two first steps with a create table with select:
CREATE TABLE tmp_table AS SELECT id, name FROM src_table
When I ran "CREATE TABLE tmp_table AS SELECT id, name FROM src_table", I lost all the column type formatting (e.g., time field turned into a integer field
As initially stated seems like it should be easier, but here is what I did to fix. I had this problem b/c I wanted to change the Not Null field in a column and Sqlite doesnt really help there.
Using the 'SQLite Manager' Firefox addon browser (use what you like). I created the new table by copying the old create statement, made my modification, and executed it. Then to get the data copied over, I just highlighted the rows, R-click 'Copy Row(s) as SQL', replaced "someTable" with my table name, and executed the SQL.
Various good answers already given to this question, but I also suggest taking a look at the sqlite.org page on ALTER TABLE which covers this issue in some detail: What (few) changes are possible to columns (RENAME|ADD|DROP) but also detailed workarounds for other operations in the section Making Other Kinds Of Table Schema Changes and background info in Why ALTER TABLE is such a problem for SQLite. In particular the workarounds point out some pitfalls when working with more complex tables and explain how to make changes safely.
I've got a flex/air app I've been working on, it uses a local sqlite database that is created on the initial application start.
I've added some features to the application and in the process I had to add a new field to one of the database tables. My questions is how to I go about getting the application to create one new field that is located in a table that already exists?
this is a the line that creates the table
stmt.text = "CREATE TABLE IF NOT EXISTS tbl_status ("+"status_id INTEGER PRIMARY KEY AUTOINCREMENT,"+" status_status TEXT)";
And now I'd like to add a status_default field.
thanks!
Thanks - MPelletier
I've add the code you provided and it does add the field, but now the next time I restart my app I get an error - 'status_default' already exists'.
So how can I go about adding some sort of a IF NOT EXISTS statement to the line you provided?
ALTER TABLE tbl_status ADD COLUMN status_default TEXT;
http://www.sqlite.org/lang_altertable.html
That being said, adding columns in SQLite is limited. You cannot add a column anywhere but after the last column in your table.
As for checking if the column already exists, PRAGMA table_info(tbl_status); will return a table listing the various columns of your table.
ADD ON:
I've been using a strategy in database design that allows me to distinguish which modifications are required. For this, you will need a new table (call it DBInfo), with one field (Integer, call it SchemaVersion). Alternately, there is also an internal value in SQLite called user_version, which can be set with a PRAGMA command. Your code can, on program startup, check for schema version number and apply changes accordingly, one version at a time.
Suppose a function named UpdateDBSchema(). This function will check for your database schema version, handle DBInfo not being there, and determine that the database is in version 0. The rest of this function could be just a large switch with different versions, nested in a loop (or other structure available to your platform of choice).
So for this first version, have an UpgradeDBVersion0To1() function, which will create this new table (DBInfo), add your status_default field, and set SchemaVersion to 1. In your code, add a constant that indicates the latest schema version, say LATEST_DB_VERSION, and set it to 1. In that way, your code and your database have a schema version, and you know you need to synch them if they are not equal.
When you need to make another change to your schema, set the LATEST_DB_VERSION constant to 2 and make a new UpgradeDBVersion1To2() function that will perform the required changes.
That way, your program can be ported easily, can connect to and upgrade an old database, etc.
I know this is an old question... however.
I've hit this precise problem in the SQLite implementation in Adobe AIR. I thought it would be possible to use the PRAGMA command to resolve, but since adobe air's implementation does not support the PRAGMA command, we need an alternative.
What I did, that I thought would be worth while sharing here, is this:
var sql:SQLStatement = new SQLStatement();
sql.sqlConnection = pp_db.dbConn;
sql.text = "SELECT NewField FROM TheTable";
sql.addEventListener(SQLEvent.RESULT, function(evt:SQLEvent):void {
});
sql.addEventListener(SQLErrorEvent.ERROR, function(err:SQLErrorEvent):void {
var sql:SQLStatement = new SQLStatement();
sql.sqlConnection = pp_db.dbConn;
sql.text = "ALTER TABLE TheTable ADD COLUMN NewField NUMERIC;";
sql.execute();
sql.addEventListener(SQLEvent.RESULT, function (evt:SQLEvent):void {
});
});
sql.execute();
Hope it helps someone.
I solved a similar problem using the answer from this question:
ALTER TABLE ADD COLUMN IF NOT EXISTS in SQLite
Use built in user_version parameter to keep track of your updates. You set it using:
PRAGMA user_version = 1
and you retrieve it using
PRAGMA user_version
So basically retrieve user_version (it's 0 by default), check if it's 0. If yes, perform your updates and set it to 1. If you have more updates in the future, check if it's 1, perform updates and set it to 0. And so on...
In some cases I execute the command and get the exception for "duplicate column". Just a quick solution, not the perfect.