I want to enable constraint but don't validate existing record. only validate future record in db2.
This should be apply for check constraint.
alter table table_name add check (column_name <> '')
DB2 hast the ENFORCED and NOT ENFORCED options for check constraints. The syntax for constraints is part of the CREATE TABLE and ALTER TABLE statements. A sub-option is to either set TRUSTED or NOT TRUSTED depending on the quality of your data.
Something like the following should work:
alter table mytable add check (column1>myvalue) not enforced trusted
try Something like this
ALTER TABLE YOURLIB.YOURTABLE DROP CONSTRAINT YOURLIB.YOURCONSTRAINTNAME1;
ALTER TABLE YOURLIB.YOURTABLE ADD CONSTRAINT YOURLIB.YOURCONSTRAINTNAME1 CHECK (YOUCOLUMNNAME<>'') NOT ENFORCED TRUSTED;
Related
I have an ALTER TABLE statement, written in T-SQL (SQL Server):
ALTER TABLE myTable WITH CHECK ADD CONSTRAINT [FK_myTable_myColumn] FOREIGN KEY(myColumn) REFERENCES otherTable (Column)
If I want to translate this statement in Postgresql, how can I make this? Paying attention to WITH CHECK ADD CONSTRAINT
You need to
remove WITH CHECK - I don't know what this is supposed to do, but you can't have a "check constraint" together with a foreign key constraint in Postgres
use standard compliant identifiers (without the square brackets)
ALTER TABLE my_table
ADD CONSTRAINT fk_mytable_mycolumn
FOREIGN KEY(my_column) REFERENCES other_table (column)
Below I have a string I am attempting to execute in postgres, but I am receiving an SQL state error (42601) which I understand to be a syntax issue.
I have checked through the documentation on executing this statement and feel as though I have it correct. Any syntactical suggestions in order to correct this statement would be greatly appreviated.
ALTER TABLE ASeriesResults ADD CONSTRAINT DF_ASeriesResults_CaseId
DEFAULT ((0)) FOR CaseId;
Why are you adding a constraint if you want a default value?
A default value is not a constraint (and I don't think anything in the manual suggests that you need add constraint to add a default value):
ALTER TABLE ASeriesResults ALTER COLUMN CaseId SET DEFAULT 0;
I am trying to add an identity column in a table through alter query using Ingres DB. While creating the table, i am able to define the identity column but not when i am trying to add it through alter query. Kindly Suggest me an alter query for it.
It's not as straightforward as you might think, "alter table" has a a number of restrictions which make this a multi-step operation. Try this:
create table something(a integer, b varchar(20)) with page_size=8192;
alter table something add column c integer not null with default;
modify something to reconstruct;
alter table something alter column c integer not null generated always as identity;
modify something to reconstruct;
I ran this DDL to add an exclusion constraint to a table:
ALTER TABLE recurring_charges
ADD EXCLUDE USING GIST (period WITH &&);
Now I want to remove the constraint - how do I do that? I tried some variations of ALTER TABLE ... DROP EXCLUDE and DROP CONSTRAINT but nothing seems to work.
Figured it out - looks like it generated a name for the constraint that I have to use.
ALTER TABLE recurring_charges
DROP CONSTRAINT recurring_charges_period_excl;
And now I've updated my original DDL to use the full ADD CONSTRAINT syntax so that I can name my constraint rather than relying on automatic naming behavior:
ALTER TABLE recurring_charges
ADD CONSTRAINT recurring_charges_period_excl EXCLUDE USING GIST (period WITH &&);
To add to the above answer, to find out the constraint name, you can find it in psql using:
\d+ tableName
If I script a table with a foreign key, it looks like this:
GO
ALTER TABLE [dbo].[MyTable] WITH CHECK ADD CONSTRAINT [FK_MyTable_SomeCol] FOREIGN KEY([SomeCol])
REFERENCES [dbo].[MyOtherTable] ([SomeCol])
GO
ALTER TABLE [dbo].[MyTable] CHECK CONSTRAINT [FK_MyTable_SomeCol]
GO
What is the second part for (ALTER TABLE [dbo].[MyTable] CHECK CONSTRAINT [FK_MyTable_SomeCol])?
It's an artifact of the way that the constraint is scripted - although it's unnecessary to specify these options (since they're the defaults for new constraints), the same generator can also generate NOCHECK options in exactly the same manner.
Documentation for ALTER TABLE indicates two distinct uses of CHECK/NOCHECK:
WITH CHECK | WITH NOCHECK
Specifies whether the data in the table is or is not validated against a newly added or re-enabled FOREIGN KEY or CHECK constraint. If not specified, WITH CHECK is assumed for new constraints, and WITH NOCHECK is assumed for re-enabled constraints.
And:
{ CHECK | NOCHECK } CONSTRAINT
Specifies that constraint_name is enabled or disabled.
So one option is saying "check the current contents of the table", the other is saying "Validate new data as it is added".
This is a way of implementing referential integrity for your tables.