The documentation for SQLite FTS implies that FTS tables should be populated and updated using INSERT, UPDATE, DELETE, etc.
That's what I was doing - adding rows, deleting them, etc., but recently I've noticed that as soon as I create the FTS table, it is automatically populated using the data from the source. I create it this way:
CREATE VIRTUAL TABLE notes_fts USING fts4(content="notes", notindexed="id", id, title, body)
If I add a row to the "notes" table, it is also automatically added to notes_fts. I guess that's what virtual tables are.
But then, why is there a chapter about populating FTS tables? What would even be the point since for example if I delete a row, it will come back if it's still in the source table.
Any idea about this? Do FTS actually need to be populated?
After further reading I found that the FTS table indeed need to be manually kept in sync with the content table. When running the CREATE VIRTUAL TABLE call, the FTS table is automatically populated but after that deletions, insertions and updates have to be done manually.
In my case I've done it using the following triggers:
CREATE VIRTUAL TABLE notes_fts USING fts4(content="notes", notindexed="id", id, title, body
CREATE TRIGGER notes_fts_before_update BEFORE UPDATE ON notes BEGIN
DELETE FROM notes_fts WHERE docid=old.rowid;
END
CREATE TRIGGER notes_fts_before_delete BEFORE DELETE ON notes BEGIN
DELETE FROM notes_fts WHERE docid=old.rowid;
END
CREATE TRIGGER notes_after_update AFTER UPDATE ON notes BEGIN
INSERT INTO notes_fts(docid, id, title, body) SELECT rowid, id, title, body FROM notes WHERE is_conflict = 0 AND encryption_applied = 0 AND new.rowid = notes.rowid;
END
CREATE TRIGGER notes_after_insert AFTER INSERT ON notes BEGIN
INSERT INTO notes_fts(docid, id, title, body) SELECT rowid, id, title, body FROM notes WHERE is_conflict = 0 AND encryption_applied = 0 AND new.rowid = notes.rowid;
END;
According to sqlite document
To delete entry, either
-- Insert a row with rowid=14 into the fts5 table.
INSERT INTO ft(rowid, a, b, c) VALUES(14, $a, $b, $c);
-- Remove the same row from the fts5 table.
INSERT INTO ft(ft, rowid, a, b, c) VALUES('delete', 14, $a, $b, $c);
or
CREATE TRIGGER tbl_ad AFTER DELETE ON tbl BEGIN
INSERT INTO fts_idx(fts_idx, rowid, b, c) VALUES('delete', old.a, old.b, old.c);
END;
To rebuild based on the modified virtual table
INSERT INTO ft(ft) VALUES('rebuild');
Related
insert into dbo.OffEmployeeRecord
select * from dbo.EmployeeRecord where Code=1
this code copies data from table_1 to table_2 but i want to move it( deletion after copy from first table) in single query
You can write stored procedures to perform such action
createProc [dbo].[ProcRemoveEmoRecord]
(
#CodId varchar(50)
)
As
begin
insert into dbo.OffEmployeeRecord
select * from dbo.EmployeeRecord where Code=#CodId
delete from dbo.EmployeeRecord where Code=#CodId
end
after creating the above sp, you can perform the required action by executing the above procedure
I have 3 tables tblpermission, tblgroup, tblassigngrouppermission. Then I have a design there have two comboboxes for selecting group and permission. After select I add it to a listview. Then I save it, at that time it will go to the table tblassigngrouppermission.
That table has columns such as assign id (default increment), groupid, permission id. All are correctly added to the table. After that saving if I select the same group for assign permission. Then I select already assigned permission and click save it added to the table. But I need there not add the already assigned permission to the table.
How can I do this?
When you are saving the data back to tblassigngrouppermission you will have to check the presence of group_id and permission_id in the table.
if they are present you will have to update tblassigngrouppermission else you will have to insert in tblassigngrouppermission
If you are using stored procedure you could do this
IF NOT EXISTS(Select permissionId From tblassigngrouppermission
Where groupId=#GroupID AND permissionId=#permissionId)
Begin
INSERT INTO tblassigngrouppermission(groupId,permissionId) Values(#groupId, #PermissionID)
End
You can also check from your code
==> Write a function that test if the permission already exist
bool GroupPermissionExists(int groupId, int permissionId)
{
//Select Where GroupId=groupId AND PermissionID=permissionId
}
if(!GroupPermissionExists(10, 123))
{
AddPermissionToGroup(10, 123);
}
im creating (in Qt )
QString q = "CREATE VIRTUAL TABLE playlist USING fts3 ("
"from_user , "
"from_id , "
"created_time , "
"created_time_formated , "
"user_id unique )";
then execute
"INSERT OR IGNORE INTO play_list (from_user,from_id,created_time,created_time_formated,user_id) SELECT '....','....','.....','....','123'"
im using full Full-Text Search so this is way im using VIRTUAL TABLE
if i have another row with user_id == 123 it will still insert the row , why ?
The FTS documentation states that:
The same applies to any constraints specified along with an FTS column name - they are parsed but not used or recorded by the system in any way.
So the UNIQUE constraint is ignored.
You can emulate the constraint by using a trigger on a view (not on the table because triggers are not available on virtual tables), and then by inserting the row on that view:
CREATE VIEW playlist_view AS SELECT * FROM playlist;
CREATE TRIGGER insert_playlist INSTEAD OF INSERT ON playlist_view
BEGIN
SELECT RAISE(ABORT, 'column user_id is not unique') FROM playlist
WHERE user_id=new.user_id;
INSERT INTO playlist (from_user, from_id, created_time,
created_time_formated, user_id)
VALUES (NEW.from_user, NEW.from_id, NEW.created_time,
NEW.created_time_formated, NEW.user_id);
END;
-- And you do the insertion on the view
INSERT INTO playlist_view (from_user,from_id,created_time,created_time_formated,user_id) SELECT ...;
Because OR IGNORE won't ignore an explicit RAISE, if you want to ignore the error, you have to replace RAISE(ABORT,...) by RAISE(IGNORE).
I need to get column names and their tables in a SQLite database. What I need is a resultset with 2 columns: table_name | column_name.
In MySQL, I'm able to get this information with a SQL query on database INFORMATION_SCHEMA. However the SQLite offers table sqlite_master:
sqlite> create table students (id INTEGER, name TEXT);
sqlite> select * from sqlite_master;
table|students|students|2|CREATE TABLE students (id INTEGER, name TEXT)
which results a DDL construction query (CREATE TABLE) which is not helpful for me and I need to parse this to get relevant information.
I need to get list of tables and join them with columns or just get columns along with table name column. So PRAGMA table_info(TABLENAME) is not working for me since I don't have table name. I want to get all column metadata in the database.
Is there a better way to get that information as a result set by querying database?
You've basically named the solution in your question.
To get a list of tables (and views), query sqlite_master as in
SELECT name, sql FROM sqlite_master
WHERE type='table'
ORDER BY name;
(see the SQLite FAQ)
To get information about the columns in a specific table, use PRAGMA table_info(table-name); as explained in the SQLite PRAGMA documentation.
I don't know of any way to get tablename|columnname returned as the result of a single query. I don't believe SQLite supports this. Your best bet is probably to use the two methods together to return the information you're looking for - first get the list of tables using sqlite_master, then loop through them to get their columns using PRAGMA table_info().
Recent versions of SQLite allow you to select against PRAGMA results now, which makes this easy:
SELECT
m.name as table_name,
p.name as column_name
FROM
sqlite_master AS m
JOIN
pragma_table_info(m.name) AS p
ORDER BY
m.name,
p.cid
where p.cid holds the column order of the CREATE TABLE statement, zero-indexed.
David Garoutte answered this here, but this SQL should execute faster, and columns are ordered by the schema, not alphabetically.
Note that table_info also contains
type (the datatype, like integer or text),
notnull (1 if the column has a NOT NULL constraint)
dflt_value (NULL if no default value)
pk (1 if the column is the table's primary key, else 0)
RTFM: https://www.sqlite.org/pragma.html#pragma_table_info
There are ".tables" and ".schema [table_name]" commands which give kind of a separated version to the result you get from "select * from sqlite_master;"
There is also "pragma table_info([table_name]);" command to get a better result for parsing instead of a construction query:
sqlite> .tables
students
sqlite> .schema students
create table students(id INTEGER, name TEXT);
sqlite> pragma table_info(students);
0|id|INTEGER|0||0
1|name|TEXT|0||0
Hope, it helps to some extent...
Another useful trick is to first get all the table names from sqlite_master.
Then for each one, fire off a query "select * from t where 1 = 0". If you analyze the structure of the resulting query - depends on what language/api you're calling it from - you get a rich structure describing the columns.
In python
c = ...db.cursor()
c.execute("select * from t where 1=0");
c.fetchall();
print c.description;
Juraj
PS. I'm in the habit of using 'where 1=0' because the record limiting syntax seems to vary from db to db. Furthermore, a good database will optimize out this always-false clause.
The same effect, in SQLite, is achieved with 'limit 0'.
FYI, if you're using .Net you can use the DbConnection.GetSchema method to retrieve information that usually is in INFORMATION_SCHEMA. If you have an abstraction layer you can have the same code for all types of databases (NOTE that MySQL seems to swich the 1st 2 arguments of the restrictions array).
Try this sqlite table schema parser, I implemented the sqlite table parser for parsing the table definitions in PHP.
It returns the full definitions (unique, primary key, type, precision, not null, references, table constraints... etc)
https://github.com/maghead/sqlite-parser
The syntax follows sqlite create table statement syntax: http://www.sqlite.org/lang_createtable.html
This is an old question but because of the number of times it has been viewed we are adding to the question for the simple reason most of the answers tell you how to find the TABLE names in the SQLite Database
WHAT DO YOU DO WHEN THE TABLE NAME IS NOT IN THE DATABASE ?
This is happening to our app because we are creating TABLES programmatically
So the code below will deal with the issue when the TABLE is NOT in or created by the Database Enjoy
public void toPageTwo(View view){
if(etQuizTable.getText().toString().equals("")){
Toast.makeText(getApplicationContext(), "Enter Table Name\n\n"
+" OR"+"\n\nMake Table First", Toast.LENGTH_LONG
).show();
etQuizTable.requestFocus();
return;
}
NEW_TABLE = etQuizTable.getText().toString().trim();
db = dbHelper.getWritableDatabase();
ArrayList<String> arrTblNames = new ArrayList<>();
Cursor c = db.rawQuery("SELECT name FROM sqlite_master WHERE
type='table'", null);
if (c.moveToFirst()) {
while ( !c.isAfterLast() ) {
arrTblNames.add( c.getString( c.getColumnIndex("name")) );
c.moveToNext();
}
}
c.close();
db.close();
boolean matchFound = false;
for(int i=0;i<arrTblNames.size();i++) {
if(arrTblNames.get(i).equals(NEW_TABLE)) {
Intent intent = new Intent(ManageTables.this, TableCreate.class
);
startActivity( intent );
matchFound = true;
}
}
if (!matchFound) {
Toast.makeText(getApplicationContext(), "No Such Table\n\n"
+" OR"+"\n\nMake Table First", Toast.LENGTH_LONG
).show();
etQuizTable.requestFocus();
}
}
I've found a few "would be" solutions for the classic "How do I insert a new record or update one if it already exists" but I cannot get any of them to work in SQLite.
I have a table defined as follows:
CREATE TABLE Book
ID INTEGER PRIMARY KEY AUTOINCREMENT,
Name VARCHAR(60) UNIQUE,
TypeID INTEGER,
Level INTEGER,
Seen INTEGER
What I want to do is add a record with a unique Name. If the Name already exists, I want to modify the fields.
Can somebody tell me how to do this please?
Have a look at http://sqlite.org/lang_conflict.html.
You want something like:
insert or replace into Book (ID, Name, TypeID, Level, Seen) values
((select ID from Book where Name = "SearchName"), "SearchName", ...);
Note that any field not in the insert list will be set to NULL if the row already exists in the table. This is why there's a subselect for the ID column: In the replacement case the statement would set it to NULL and then a fresh ID would be allocated.
This approach can also be used if you want to leave particular field values alone if the row in the replacement case but set the field to NULL in the insert case.
For example, assuming you want to leave Seen alone:
insert or replace into Book (ID, Name, TypeID, Level, Seen) values (
(select ID from Book where Name = "SearchName"),
"SearchName",
5,
6,
(select Seen from Book where Name = "SearchName"));
You should use the INSERT OR IGNORE command followed by an UPDATE command:
In the following example name is a primary key:
INSERT OR IGNORE INTO my_table (name, age) VALUES ('Karen', 34)
UPDATE my_table SET age = 34 WHERE name='Karen'
The first command will insert the record. If the record exists, it will ignore the error caused by the conflict with an existing primary key.
The second command will update the record (which now definitely exists)
You need to set a constraint on the table to trigger a "conflict" which you then resolve by doing a replace:
CREATE TABLE data (id INTEGER PRIMARY KEY, event_id INTEGER, track_id INTEGER, value REAL);
CREATE UNIQUE INDEX data_idx ON data(event_id, track_id);
Then you can issue:
INSERT OR REPLACE INTO data VALUES (NULL, 1, 2, 3);
INSERT OR REPLACE INTO data VALUES (NULL, 2, 2, 3);
INSERT OR REPLACE INTO data VALUES (NULL, 1, 2, 5);
The "SELECT * FROM data" will give you:
2|2|2|3.0
3|1|2|5.0
Note that the data.id is "3" and not "1" because REPLACE does a DELETE and INSERT, not an UPDATE. This also means that you must ensure that you define all necessary columns or you will get unexpected NULL values.
INSERT OR REPLACE will replace the other fields to default value.
sqlite> CREATE TABLE Book (
ID INTEGER PRIMARY KEY AUTOINCREMENT,
Name TEXT,
TypeID INTEGER,
Level INTEGER,
Seen INTEGER
);
sqlite> INSERT INTO Book VALUES (1001, 'C++', 10, 10, 0);
sqlite> SELECT * FROM Book;
1001|C++|10|10|0
sqlite> INSERT OR REPLACE INTO Book(ID, Name) VALUES(1001, 'SQLite');
sqlite> SELECT * FROM Book;
1001|SQLite|||
If you want to preserve the other field
Method 1
sqlite> SELECT * FROM Book;
1001|C++|10|10|0
sqlite> INSERT OR IGNORE INTO Book(ID) VALUES(1001);
sqlite> UPDATE Book SET Name='SQLite' WHERE ID=1001;
sqlite> SELECT * FROM Book;
1001|SQLite|10|10|0
Method 2
Using UPSERT (syntax was added to SQLite with version 3.24.0 (2018-06-04))
INSERT INTO Book (ID, Name)
VALUES (1001, 'SQLite')
ON CONFLICT (ID) DO
UPDATE SET Name=excluded.Name;
The excluded. prefix equal to the value in VALUES ('SQLite').
Firstly update it. If affected row count = 0 then insert it. Its the easiest and suitable for all RDBMS.
Upsert is what you want. UPSERT syntax was added to SQLite with version 3.24.0 (2018-06-04).
CREATE TABLE phonebook2(
name TEXT PRIMARY KEY,
phonenumber TEXT,
validDate DATE
);
INSERT INTO phonebook2(name,phonenumber,validDate)
VALUES('Alice','704-555-1212','2018-05-08')
ON CONFLICT(name) DO UPDATE SET
phonenumber=excluded.phonenumber,
validDate=excluded.validDate
WHERE excluded.validDate>phonebook2.validDate;
Be warned that at this point the actual word "UPSERT" is not part of the upsert syntax.
The correct syntax is
INSERT INTO ... ON CONFLICT(...) DO UPDATE SET...
and if you are doing INSERT INTO SELECT ... your select needs at least WHERE true to solve parser ambiguity about the token ON with the join syntax.
Be warned that INSERT OR REPLACE... will delete the record before inserting a new one if it has to replace, which could be bad if you have foreign key cascades or other delete triggers.
If you have no primary key, You can insert if not exist, then do an update. The table must contain at least one entry before using this.
INSERT INTO Test
(id, name)
SELECT
101 as id,
'Bob' as name
FROM Test
WHERE NOT EXISTS(SELECT * FROM Test WHERE id = 101 and name = 'Bob') LIMIT 1;
Update Test SET id='101' WHERE name='Bob';
I believe you want UPSERT.
"INSERT OR REPLACE" without the additional trickery in that answer will reset any fields you don't specify to NULL or other default value. (This behavior of INSERT OR REPLACE is unlike UPDATE; it's exactly like INSERT, because it actually is INSERT; however if what you wanted is UPDATE-if-exists you probably want the UPDATE semantics and will be unpleasantly surprised by the actual result.)
The trickery from the suggested UPSERT implementation is basically to use INSERT OR REPLACE, but specify all fields, using embedded SELECT clauses to retrieve the current value for fields you don't want to change.
I think it's worth pointing out that there can be some unexpected behaviour here if you don't thoroughly understand how PRIMARY KEY and UNIQUE interact.
As an example, if you want to insert a record only if the NAME field isn't currently taken, and if it is, you want a constraint exception to fire to tell you, then INSERT OR REPLACE will not throw and exception and instead will resolve the UNIQUE constraint itself by replacing the conflicting record (the existing record with the same NAME). Gaspard's demonstrates this really well in his answer above.
If you want a constraint exception to fire, you have to use an INSERT statement, and rely on a separate UPDATE command to update the record once you know the name isn't taken.