I'm changing constraints in my database and I need to drop some of them. I know that for a single constraint, the command is following:
ALTER TABLE tblApplication DROP CONSTRAINT constraint1_name;
However, when I try
ALTER TABLE tblApplication DROP (
CONSTRAINT constraint1_name,
CONSTRAINT constraint2_name,
CONSTRAINT constraint3_name
);
it doesn't work and I need to do:
ALTER TABLE tblApplication DROP CONSTRAINT constraint1_name;
ALTER TABLE tblApplication DROP CONSTRAINT constraint2_name;
ALTER TABLE tblApplication DROP CONSTRAINT constraint3_name;
Is there a way to remove more than one constraint in a single command? I'd like to avoid repeating ALTER TABLE tblApplication, just like with the ADD command:
ALTER TABLE tblApplication ADD (
CONSTRAINT contraint1_name FOREIGN KEY ... ENABLE,
CONSTRAINT contraint2_name FOREIGN KEY ... ENABLE,
CONSTRAINT contraint3_name FOREIGN KEY ... ENABLE
);
Yes you can. You just need to repeat 'drop constraint' per constraint. e.g.
alter table t1
drop constraint fk1
drop constraint fk2
/
Edit: I tested this against Oracle 11, and it worked fine. Don't know about older versions.
There is an alternative form to drop constraints related to a column in a table, also dropping the column with CASCADE:
ALTER TABLE table1 DROP (columnName) CASCADE CONSTRAINTS;
It is tested on Oracle 11g
example: we can drop constraints in MySQL by creating constraints to the variables like this way.
create table sample(id int, name varchar(30), marks int, constraint uid unique(id), constraint un unique(name));
alter table sample drop constraint uid, drop constraint un;
Yes, we can drop multiple at once:
ALTER TABLE TABLE NAME
DROP CONSTRAINTS CONSTRAINT VALUE
DROP CONSTRAINTS CONSTRAINT VALUE;
Related
How do I alter a table to have a column a foreign key constraint with a default value?
In T-SQL if you're using SQL-Server, just be careful to put a real key for default.
Edit: As said in the comments, be careful that you really need a default value for a foreign key, there could be a design problem.
ALTER TABLE [tablename]
ADD CONSTRAINT [CK_columnname_default]
DEFAULT [your_default_value] FOR [columnname];
GO
ALTER TABLE [tablename]
ADD CONSTRAINT [FK_nameForeignKey] FOREIGN KEY (columnname)
REFERENCES [dbo].[oTable] (oTableID)
ON UPDATE CASCADE;
GO
Well I did the following and it worked for me:
ALTER TABLE Employee
ADD RegionID varchar(3)
CONSTRAINT [Default_Value_Region] default ('US') NOT NULL,
CONSTRAINT [FK_EMPLOYEE_Region] FOREIGN KEY([RegionID])
REFERENCES [dbo].[Region] ([Code])
GO
ALTER TABLE table1
ADD FOREIGN KEY attrib1 REFERENCES table2(attrib2)
GO
It works - but how can I drop it?
If I try
DROP FOREIGN KEY (attrib1) REFERENCES table2(attrib2)
it says
Incorrect syntax near the keyword 'FOREIGN'.
In SQL Server you need to drop foreign key constraint by using below query:
Query :
ALTER TABLE [dbo].[Table_Name]
DROP CONSTRAINT [Constraint_Name]
Example:
ALTER TABLE [dbo].[SpeakerDetail]
DROP CONSTRAINT [FK_SpeakerId_UserID]
MS SQL Server
I'm making a star schema. I've set the PK's and FK for my tables and am now trying to write a procedure that will drop the constraints, truncate the tables, add the constraints again, and then repopulate the tables. When I try to drop the constraints I receive the error:
"The constraint PK_TIMEDIM is being referenced by table SalesFactTable, foreign key constraint FK_SALESFACTTABLE. Could not drop constraint."
EDIT: One problem solved. Another found. I receive the same error except now there are mysterious, auto-generated FK's such as FK__SalesFact__CUST___19DFD96B.
Please show me what I'm doing wrong.
ALTER PROCEDURE [dbo].[A11]
AS
BEGIN
--Drop constraints
ALTER TABLE SalesFactTable
DROP CONSTRAINT FK_SALESFACTTABLE
ALTER TABLE SalesFactTable
DROP CONSTRAINT PK_SALESFACTTABLE
ALTER TABLE TimeDim
DROP CONSTRAINT PK_TIMEDIM
ALTER TABLE CustomerDim
DROP CONSTRAINT PK_CUSTOMERDIM
ALTER TABLE PartDim
DROP CONSTRAINT PK_PARTDIM
--Truncate tables
TRUNCATE TABLE TimeDim
TRUNCATE TABLE CustomerDim
TRUNCATE TABLE PartDim
TRUNCATE TABLE SalesFactTable
--Add constraints
ALTER TABLE TimeDim
ADD CONSTRAINT PK_TIMEDIM PRIMARY KEY (TIME_ID)
ALTER TABLE CustomerDim
ADD CONSTRAINT PK_CUSTOMERDIM PRIMARY KEY (CUST_ID)
ALTER TABLE PartDim
ADD CONSTRAINT PK_PARTDIM PRIMARY KEY (PART_ID)
ALTER TABLE SalesFactTable
ADD CONSTRAINT FK_SALESFACTTABLE FOREIGN KEY (TIME_ID) REFERENCES TimeDim (TIME_ID),
FOREIGN KEY (CUST_ID) REFERENCES CustomerDim (CUST_ID),
FOREIGN KEY (PART_ID) REFERENCES PartDim (PART_ID)
ALTER TABLE SalesFactTable
ADD CONSTRAINT PK_SALESFACTTABLE PRIMARY KEY (TIME_ID, CUST_ID, PART_ID)
**Foreign keys are referenced by the Primary key, so you are not allowed to remove the primary key before removing the Foreign Key constraint.
so, you need to remove the foreign key first to remove the Primary key constraint from a table.
**
ALTER PROCEDURE [dbo].[A11]
AS
BEGIN
--Drop FK constraints
ALTER TABLE SalesFactTable
DROP CONSTRAINT FK_SALESFACTTABLE
--Drop PK constraints
ALTER TABLE SalesFactTable
DROP CONSTRAINT PK_SALESFACTTABLE
ALTER TABLE TimeDim
DROP CONSTRAINT PK_TIMEDIM
ALTER TABLE CustomerDim
DROP CONSTRAINT PK_CUSTOMERDIM
ALTER TABLE PartDim
DROP CONSTRAINT PK_PARTDIM
--Truncate tables
TRUNCATE TABLE TimeDim
TRUNCATE TABLE CustomerDim
TRUNCATE TABLE PartDim
TRUNCATE TABLE SalesFactTable
--Add constraints
ALTER TABLE TimeDim
ADD CONSTRAINT PK_TIMEDIM PRIMARY KEY (TIME_ID)
ALTER TABLE CustomerDim
ADD CONSTRAINT PK_CUSTOMERDIM PRIMARY KEY (CUST_ID)
ALTER TABLE PartDim
ADD CONSTRAINT PK_PARTDIM PRIMARY KEY (PART_ID)
ALTER TABLE SalesFactTable
ADD CONSTRAINT FK_SALESFACTTABLE FOREIGN KEY (TIME_ID) REFERENCES TimeDim (TIME_ID),
FOREIGN KEY (CUST_ID) REFERENCES CustomerDim (CUST_ID),
FOREIGN KEY (PART_ID) REFERENCES PartDim (PART_ID)
ALTER TABLE SalesFactTable
ADD CONSTRAINT PK_SALESFACTTABLE PRIMARY KEY (TIME_ID, CUST_ID, PART_ID)
SQL How to Alter Constraint
Below is 1 of my constraint
CONSTRAINT ACTIVEPROG_FKEY1 FOREIGN KEY(ActiveProgCode) REFERENCES PROGRAM(ActiveProgCode),
I want to add in
ON DELETE CASCADE
to the constraint above.
How do i alter that existing constraint ACTIVEPROG_FKEY1 and add
ON DELETE CASCADE
to constraint ACTIVEPROG_FKEY1
Consider ACTIVEPROG_FKEY1 is at Table ACTIVEPROG
You can not alter constraints ever but you can drop them and then recreate.
Have look on this
ALTER TABLE your_table DROP CONSTRAINT ACTIVEPROG_FKEY1;
and then recreate it with ON DELETE CASCADE like this
ALTER TABLE your_table
add CONSTRAINT ACTIVEPROG_FKEY1 FOREIGN KEY(ActiveProgCode) REFERENCES PROGRAM(ActiveProgCode)
ON DELETE CASCADE;
hope this help
No. We cannot alter the constraint, only thing we can do is drop and recreate it
ALTER TABLE [TABLENAME] DROP CONSTRAINT [CONSTRAINTNAME]
Foreign Key Constraint
Alter Table Table1 Add Constraint [CONSTRAINTNAME] Foreign Key (Column) References Table2 (Column) On Update Cascade On Delete Cascade
Primary Key constraint
Alter Table Table add constraint [Primary Key] Primary key(Column1,Column2,.....)
I'm trying to move a primary key constraint to a different column in oracle. I tried this:
ALTER TABLE MY_TABLE
DROP CONSTRAINT c_name;
ALTER TABLE MY_TABLE
ADD CONSTRAINT c_name PRIMARY KEY
(
"COLUMN_NAME"
) ENABLE;
This fails on the add constraint with an error saying the the constraint already exists even though i just dropped it. Any ideas why this is happening
If the original constraint was a primary key constraint, Oracle creates an index to enforce the constraint. This index has the same name as the constraint (C_NAME in your example). You need to drop the index separately from the constraint. So you will need to do a :
ALTER TABLE <table1> DROP CONSTRAINT C_NAME;
DROP INDEX C_NAME;
ALTER TABLE <table1> ADD CONSTRAINT C_NAME PRIMARY KEY
( COLUMN_2 ) ENABLE;
The safest way is to first add a unique index. Try this:
create unique index new_pk on <tabname> (column_2);
Then drop the old PK:
alter table <tabname> drop primary key drop index;
(Optional) Rename the index:
alter index new_pk rename to c_name;
And then add the PK again indicating the index to be used:
alter table <tabname> add constraint c_name
primary key (column_2) using index c_name;
I don't know if this is a similar problem but, in DB2, you have to actually commit following the alter table statement. Otherwise it's still hanging around.