alter-table

How do I use ALTER TABLE to add a new column and make it unique? Depends on the DBMS, but I think the following is quite portable: ALTER TABLE table_name ADD column_name datatype ALTER TABLE table_name ADD UNIQUE (column_name) If you want to give a name to the UNIQUE constraint, you could replace the last command with this: ALTER TABLE table_name ADD CONSTRAINT constraint_name UNIQUE (column_name) if table is empty ALTER TABLE ADD (FieldName Type) ALTER TABLE ADD CONSTRAINT UNIQUE(FieldName) If you have data in table you need to this in three steps: Add column Fill values Add unique constraint

Is it possible to create a column and insert values to it during the same transaction? This is part of an upgrade script. I found the following method online , but it does not work; I get an error: Invalid column name 'IndexNumber'. . I'm assuming this is because the transaction hasn't created the column yet so there is nothing to insert to. The relevant parts of my script: Print 'Beginning Upgrade' Begin Transaction -- -------------------------------------------------------------------- USE [MyDatabase]; /* Widgets now can be ordered and the order can be modified */ ALTER TABLE [dbo].[Widgets

ALTER TABLE products ALTER COLUMN power_price DROP DEFAULT; ALTER TABLE products ALTER COLUMN power_price TYPE bool USING (power_price::boolean); ALTER TABLE products ALTER COLUMN power_price SET NOT NULL; ALTER TABLE products ALTER COLUMN power_price SET DEFAULT false; Postgres gives me this error: Query failed: ERROR: cannot cast type numeric to boolean Use: ALTER TABLE products ALTER power_price TYPE bool USING (power_price::int::bool); There is no direct cast defined between numeric and boolean . You can use integer as middle-ground. text would be another candidate for middle ground, since

Is it possible to rename a column in MySQL without having to repeat its type definition? Please without having to hack into information_schema. The ALTER TABLE syntax does not seem to offer such possibility: ALTER [ONLINE | OFFLINE] [IGNORE] TABLE tbl_name [alter_specification [, alter_specification] ...] [partition_options] ALTER [ONLINE | OFFLINE] [IGNORE] TABLE tbl_name partition_options alter_specification: table_options [...] | CHANGE [COLUMN] old_col_name new_col_name column_definition [FIRST|AFTER col_name] | MODIFY [COLUMN] col_name column_definition [FIRST | AFTER col_name] [...] More

How can I alter the reference to a table in PostgreSQL when the table name has been changed? Say I have: CREATE TABLE example1 ( id serial NOT NULL PRIMARY KEY, name varchar(100) ); CREATE TABLE example2 ( id serial NOT NULL PRIMARY KEY, example1fk integer REFERENCES example1 (id) DEFERRABLE INITIALLY DEFERRED ); Later I do: ALTER TABLE example1 RENAME TO example3; How to change the definition of the foreign key constraint? example1fk integer REFERENCES example1 (id) DEFERRABLE INITIALLY DEFERRED, Internal dependencies between tables and / or other objects are never bound to the object name.