ALTER TABLE a add (OWNER_NAME VARCHAR2,OWNER_PARENT VARCHAR2);
Is it possible to alter table add MULTIPLE columns in a single statement in sqlite3?
The SQLite documentation provides the following picture to illustrate how the ALTER TABLE is understood by SQLite.
So, it does not seem possible to add multiple columns in a single ALTER TABLE command.
Reference: SQLite Query Language: ALTER TABLE
EDIT:
SQLite is a bit rigid when it comes to modifying existing tables and has limited support for the ALTER TABLE query.
Some more information can be found following this link: How do I add or delete columns from an existing table in SQLite.
The link also provides a workaround to carry out complex table modifications.
In a nutshell (emphasis mine):
If you want to make more complex changes in the structure of a table, you will have to recreate the table. You can save existing data to a temporary table, drop the old table, create the new table, then copy the data back in from the temporary table.
Related
Is it possible to delete a column from an SQLlite database. I have Googled this and it seems to be impossible.
From the ALTER TABLE manual;
SQLite supports a limited subset of ALTER TABLE. The ALTER TABLE command in SQLite allows the user to rename a table or to add a new column to an existing table. It is not possible to rename a column, remove a column, or add or remove constraints from a table.
So, no, not without dropping and recreating the table.
According to the docs:
It is not possible to rename a column, remove a column, or add or
remove constraints from a table.
I guess it has to be done manually.
How do I change the default value of an existing column in a table in sqlite3?
I have a table named notes with a boolean column named hidden. The default is set to true, I want to set it to false.
I don't think you can without replacing the whole table. From the fine manual:
SQL Features That SQLite Does Not Implement
Complete ALTER TABLE support
Only the RENAME TABLE and ADD COLUMN variants of the ALTER TABLE command are supported. Other kinds of ALTER TABLE operations such as DROP COLUMN, ALTER COLUMN, ADD CONSTRAINT, and so forth are omitted.
So there is no way to modify an existing column in SQLite. I think you'll have to create a new table with the appropriate default for hidden, copy all the data over, drop the original notes table, and then rename the new one.
SQLite stays lean by purposefully omitting a lot of features.
SQLite database browser allows you to drop columns, so you could drop the column with it, and then manually add the column with the default using the sqlite3 command line tool.
Create a new database with the same schema (but your new default value), attach both, and migrate.
For deleting columns or other changes that aren't supported by the "ALTER TABLE" syntax, I create a new table, migrate date into it, drop the old table, and rename the new table to the original name.
https://stackoverflow.com/a/998652/1020467
https://www.sqlite.org/lang_altertable.html
I have a table in a MS Access 2010 Database and it can easily be split up into multiple tables. However I don't know how to do that and still keep all the data linked together. Does anyone know an easy way to do this?
I ended up just writing a bunch of Update and Append queries to create smaller tables and keep all the data synced.
You must migrate to other database system, like MSSQL, mySQL. You can't do in MsAccess replication...
Not sure what do you mean by split up into multiple tables.
Are the two tables have same structure? you want to divide the table into two pats ... means if original table has fields A,B,C,D ... then you want to split it to Table1: A,B and
Table2: C,D.
Anyways, I googled it a bit and the below links might of what you are looking for. Check them.
Split a table into related tables (MDB)
How hard is it to split a table in Access into two smaller tables?
Where do you run into trouble with the table analyzer wizard? Maybe you can work around the issue you are running into.
However, if the table analyzer wizard isn't working out, you might also consider the tactics described in http://office.microsoft.com/en-us/access-help/resolve-and-help-prevent-duplicate-data-HA010341696.aspx.
Under Microsoft Access 2012, Database Tools, Analyze table.. I use the wizard to split a large table into multiple normalized tables. Hope that helps.
Hmmm, can't you just make a copy of the table, then delete opposite items in each table leaving the data the way you want except, make sure that both tables have the same exact auto number field, and use that field to reference the other.
It may not be the most proficient way to do it, but I solved a similar issue the following way:
a) Procedure that creates a new table via SQL:
CREATE TABLE t002 (ID002 INTEGER PRIMARY KEY, CONSTRAINT SomeName FOREIGN KEY (ID002) REFERENCES t001(ID001));
The two tables are related to each other through the foreign key.
b) Procedure that adds the neccessary fields to the new table (t002). In the following sample code let's use just one field, and let's call it [MyFieldName].
c) Procedure to append all values of field ID001 from Table t001 to field ID002 in Table t002, via SQL:
INSERT INTO ID002 (t002) SELECT t001.ID001 FROM t001;
d) Procedure to transfer values from fields in t001 to fields in t001, via SQL:
UPDATE t001 INNER JOIN t002 ON t001.ID001 = t002.ID002 SET t002.MyFieldName = t001.MyFieldName;
e) Procedure to remove (drop) the fields in question in Table t001, via SQL:
ALTER TABLE t001 DROP COLUMN MyFieldName;
f) Procedure that calls them all one after the other. Fieldnames are fed into the process as parameters in the call to Procedure f.
It is quite a bunch of coding, but it did the job for me.
I need the ability to add FTS3 to a sqlite3 table after it was created, not as it is created. Does anyone know the ALTER syntax to accomplish this?
SQLite does not support altering a table from a normal table to an FTS3 table. All you can do with ALTER TABLE is change the table name or add columns.
You will have to use CREATE VIRTUAL TABLE to make the FTS3 table and then copy the data.
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.