I've come from MS SQL Server where there's an option in SSMS to allow the dropping of tables/views if required when altering them.
Is there the same option in pgAdmin for PostgreSQL?
When trying to change the type of an existing column in a table, I keep getting the error:
ERROR: cannot alter type of column used by a view or rule .... on view ... depends on column "name"
FWIW I'm changing the type from text to character varying, so it's hardly magician work
Related
I'm using Firebird 4.0 and I would convert a column from smallint 0|1 to boolean.
So I have this kind of domain:
CREATE DOMAIN D_BOOL
AS SMALLINT
DEFAULT 0
NOT NULL
CHECK (VALUE IN (0,1))
;
This domain is used in my test table:
CREATE TABLE TBOOL
(
ID INTEGER,
INTVAL D_BOOL
);
How can I convert the column INTVAL to BOOLEAN?
I tried this query but I got an error:
alter table tbool
alter column INTVAL TYPE BOOLEAN,
alter column INTVAL SET DEFAULT FALSE
Error:
Error: *** IBPP::SQLException ***
Context: Statement::Execute( alter table tbool
alter column INTVAL TYPE BOOLEAN,
alter column INTVAL SET DEFAULT FALSE )
Message: isc_dsql_execute2 failed
SQL Message : -607
This operation is not defined for system tables.
Engine Code : 335544351
Engine Message :
unsuccessful metadata update
ALTER TABLE TBOOL failed
MODIFY RDB$RELATION_FIELDS failed
Unfortunately, this is an incompatible column change, because there is no conversion defined from SMALLINT to BOOLEAN. Altering the type of a column only works for a limited combination of types (and there is no combination that allows modification to or from BOOLEAN).
The only real option is to add a new column, populate it based on the value of the old column, drop the old column and rename the new column. This can have a huge impact if this column is used in triggers, procedures and/or views.
Your options are basically:
Keep existing columns as-is, and only use BOOLEAN moving forward for new columns
Do a very invasive change to change all your columns.
If you have a lot of columns that need to change, this is likely easier to do by creating a new database from scratch and pumping the data over, than by changing the database in-place.
The background of this limitation is that Firebird doesn't actually modify existing values when changing the type of a column. Instead, it will convert values on the fly when reading rows created with an older "format version" (inserts and updates will write the new "format version").
This makes for fast DDL, but all conversions must be known to succeed. This basically means only "widening" conversions between similar types are allowed (e.g. longer (VAR)CHAR, longer integer types, etc).
It's been a while.
Using DB2 10 for z/OS, I've been asked to change a specific column in a table from decimal(7,2) to decimal(7,4). Sounds easy, right?
alter table MySchema.MyTable
alter column myColumn
set data type decimal(7,4);
But, DB2 responds with this error: "Attributes specified for column 'MYCOLUMN' are incompatible with existing column definition."
I had thought that converting from decimal(7,2) to decimal(7,4) would be pretty straightforward, but DB2 disagrees.
Outside of dropping the table and recreating it from scratch, what alternatives do I have?
Thanks in advance!
Dave
The reason Db2 doesn't like that change is you're going from from 99999.99 to 999.9999
Is that really what you want? Going from (7,2) to (9,4) would just add two more decimal places without losing any data and should be allowed by the Db.
Db2 for i gives a warning, but allows you to ignore the warning...
Create a new column ALTER ADD COLUMN of the right type, use an UPDATE to populate it, ALTER DROP COLUMN the old column. RENAME COLUMN so set the name of the original column.
Since Firebird 3, I can't modify a column type.
Before I use this kind of update:
update RDB$RELATION_FIELDS set
RDB$FIELD_SOURCE = 'MYTEXT'
where (RDB$FIELD_NAME = 'JXML') and
(RDB$RELATION_NAME = 'XMLTABLE')
because I get ISC error 335545030 ("UPDATE operation is not allowed for system table RDB$RELATION_FIELDS").
Maybe there is another way in Firebird 3?
Firebird 3 no longer allows direct updates to the system tables, as that was a way to potentially corrupt a database. See also System Tables are Now Read-only in the release notes. You will need to use DDL statements to do the modification.
It looks like you want to change the data type of a column to a domain. You will need to use alter table ... alter column ... for that. Specifically you will need to do:
alter table XMLTABLE
alter column JXML type MYTEXT;
This does come with some restrictions:
Changing the Data Type of a Column: the TYPE Keyword
The keyword TYPE changes the data type of an existing column to
another, allowable type. A type change that might result in data loss
will be disallowed. As an example, the number of characters in the new
type for a CHAR or VARCHAR column cannot be smaller than the existing
specification for it.
If the column was declared as an array, no change to its type or its
number of dimensions is permitted.
The data type of a column that is involved in a foreign key, primary
key or unique constraint cannot be changed at all.
This statement has been available since before Firebird 1 (InterBase 6.0).
Firebird 2.5 manual, chapter Data Definition (DDL) Statement, section TABLE:
ALTER TABLE tabname ALTER COLUMN colname TYPE typename
i want to ask one question about db2 sql.
when i runnig this ddl to set default value
alter table TTKR.TKR_TableName
alter TKR_column_name set default '1111-11-11'
i am getting this error and search on google i saw that reason is
650
THE ALTER STATEMENT CANNOT BE EXECUTED, REASON reason-code
reason code 22
`"ALTER TABLE SET DEFAULT and DROP DEFAULT are not allowed for tables referenced by a materialized query table or view.`"
how can i fix it ?
We have a Companies table in our database with a "Name" varchar column and its size is currently 30 characters. Our seemingly simple task of changing its size to 50 characters has turned into a bit of an issue. When trying to change it and save the changes through Sybase Central we get the following error:
[Sybase][ODBC Driver][SQL Anywhere]Illegal column definition: Name
SQLCODE: -1046
SQLSTATE: 42000
SQL Statement: ALTER TABLE "DBA"."Companies" ALTER "Name" VARCHAR(50)
We've tried various escaping characters around the column thinking it might have something to do with the word "Name" being treated differently internally by Sybase. We have no indexes or constraints on this column and have removed the single trigger that did exist just trying to isolate any potential factors. Further perplexing us, we have a Companies_a table that keeps track of all changes to the Companies table that has nearly the exact same schema including the Name column. We are able to change that column's size without issue which seems to indicate it's not necessarily an issue with the word "Name". I've gone through all the tabs in Sybase Central for this table, and don't see anything special/different about this table or this column.
Googling this issue is difficult as the word "Name" is extremely common. We have workarounds we can do (ie. creating temp column, copying, dropping & recreating the column, copying back) but if possible I'd like to understand exactly what's happening here and why.
I believe our Companies table and this column were likely created in a previous version of ASA. The inline_max column in sys.systabcol was set to null and we could not change it.
Running the following statement set the defaults:
ALTER TABLE "DBA"."Companies" ALTER "Name" inline use default prefix use default;
I was then able to run this statement without error:
ALTER TABLE "DBA"."Companies" ALTER "Name" VARCHAR(50);
Here's where I found the general concept for the fix:
Sybase SqlAnywhere forum thread
ALTER TABLE [tableName]
ALTER [ColumnName] varchar(4000) NULL