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+---- Thread: Add primary key to existing table (/Thread-Add-primary-key-to-existing-table)
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Add primary key to existing table - nerysiljyiya - 07-31-2023
I have an existing table called `Persion`. In this table I have 5 columns:
- persionId
- Pname
- PMid
- Pdescription
- Pamt
When I created this table, I set `PersionId` and `Pname` as the **primary key**.
I now want to include one more column in the primary key - PMID. How can I write an `ALTER` statement to do this? (I already have 1000 records in the table)
RE: Add primary key to existing table - estruation441499 - 07-31-2023
drop constraint and recreate it
alter table Persion drop CONSTRAINT <constraint_name>
alter table Persion add primary key (persionId,Pname,PMID)
edit:
you can find the constraint name by using the query below:
select OBJECT_NAME(OBJECT_ID) AS NameofConstraint
FROM sys.objects
where OBJECT_NAME(parent_object_id)='Persion'
and type_desc LIKE '%CONSTRAINT'
RE: Add primary key to existing table - acouchi578746 - 07-31-2023
I think something like this should work
-- drop current primary key constraint
ALTER TABLE dbo.persion
DROP CONSTRAINT PK_persionId;
GO
-- add new auto incremented field
ALTER TABLE dbo.persion
ADD pmid BIGINT IDENTITY;
GO
-- create new primary key constraint
ALTER TABLE dbo.persion
ADD CONSTRAINT PK_persionId PRIMARY KEY NONCLUSTERED (pmid, persionId);
GO
RE: Add primary key to existing table - kyeen - 07-31-2023
The PRIMARY KEY constraint uniquely identifies each record in a database table.
Primary keys must contain UNIQUE values and column cannot contain NULL Values.
-- DROP current primary key
ALTER TABLE tblPersons DROP CONSTRAINT <constraint_name>
Example:
ALTER TABLE tblPersons
DROP CONSTRAINT P_Id;
-- ALTER TABLE tblpersion
ALTER TABLE tblpersion add primary key (P_Id,LastName)
RE: Add primary key to existing table - precieuse896781 - 07-31-2023
-- create new primary key constraint
ALTER TABLE dbo.persion
ADD CONSTRAINT PK_persionId PRIMARY KEY NONCLUSTERED (pmid, persionId);
is a better solution because you have control over the naming of the primary_key.
----------
It's better than just using
ALTER TABLE Persion ADD PRIMARY KEY(persionId,Pname,PMID)
which yeilds randomized names and can cause problems when scripting out or comparing databases
RE: Add primary key to existing table - mercurated388493 - 07-31-2023
Necromancing.<br />
Just in case anybody has as good a schema to work with as me...<br />
Here is how to do it correctly:<br />
In this example, the table name is dbo.T_SYS_Language_Forms, and the column name is LANG_UID
-- First, chech if the table exists...
IF 0 < (
SELECT COUNT(*) FROM INFORMATION_SCHEMA.TABLES
WHERE TABLE_TYPE = 'BASE TABLE'
AND TABLE_SCHEMA = 'dbo'
AND TABLE_NAME = 'T_SYS_Language_Forms'
)
BEGIN
-- Check for NULL values in the primary-key column
IF 0 = (SELECT COUNT(*) FROM T_SYS_Language_Forms WHERE LANG_UID IS NULL)
BEGIN
ALTER TABLE T_SYS_Language_Forms ALTER COLUMN LANG_UID uniqueidentifier NOT NULL
-- No, don't drop, FK references might already exist...
-- Drop PK if exists (it is very possible it does not have the name you think it has...)
-- ALTER TABLE T_SYS_Language_Forms DROP CONSTRAINT pk_constraint_name
--DECLARE @pkDropCommand nvarchar(1000)
--SET @pkDropCommand = N'ALTER TABLE T_SYS_Language_Forms DROP CONSTRAINT ' + QUOTENAME((SELECT CONSTRAINT_NAME FROM INFORMATION_SCHEMA.TABLE_CONSTRAINTS
--WHERE CONSTRAINT_TYPE = 'PRIMARY KEY'
--AND TABLE_SCHEMA = 'dbo'
--AND TABLE_NAME = 'T_SYS_Language_Forms'
----AND CONSTRAINT_NAME = 'PK_T_SYS_Language_Forms'
--))
---- PRINT @pkDropCommand
--EXECUTE(@pkDropCommand)
-- Instead do
-- EXEC sp_rename 'dbo.T_SYS_Language_Forms.PK_T_SYS_Language_Forms1234565', 'PK_T_SYS_Language_Forms';
-- Check if they keys are unique (it is very possible they might not be)
IF 1 >= (SELECT TOP 1 COUNT(*) AS cnt FROM T_SYS_Language_Forms GROUP BY LANG_UID ORDER BY cnt DESC)
BEGIN
-- If no Primary key for this table
IF 0 =
(
SELECT COUNT(*) FROM INFORMATION_SCHEMA.TABLE_CONSTRAINTS
WHERE CONSTRAINT_TYPE = 'PRIMARY KEY'
AND TABLE_SCHEMA = 'dbo'
AND TABLE_NAME = 'T_SYS_Language_Forms'
-- AND CONSTRAINT_NAME = 'PK_T_SYS_Language_Forms'
)
ALTER TABLE T_SYS_Language_Forms ADD CONSTRAINT PK_T_SYS_Language_Forms PRIMARY KEY CLUSTERED (LANG_UID ASC)
;
END -- End uniqueness check
ELSE
PRINT 'FSCK, this column has duplicate keys, and can thus not be changed to primary key...'
END -- End NULL check
ELSE
PRINT 'FSCK, need to figure out how to update NULL value(s)...'
END
RE: Add primary key to existing table - scoggin320115 - 07-31-2023
Try using this code:
ALTER TABLE `table name`
CHANGE COLUMN `column name` `column name` datatype NOT NULL,
ADD PRIMARY KEY (`column name`) ;
RE: Add primary key to existing table - sheply308 - 07-31-2023
ALTER TABLE TABLE_NAME ADD PRIMARY KEY(`persionId`,`Pname`,`PMID`)
RE: Add primary key to existing table - Sirbersagliere6 - 07-31-2023
If you add primary key constraint
ALTER TABLE <TABLE NAME> ADD CONSTRAINT <CONSTRAINT NAME> PRIMARY KEY <COLUMNNAME>
for example:
ALTER TABLE DEPT ADD CONSTRAINT PK_DEPT PRIMARY KEY (DEPTNO)
RE: Add primary key to existing table - tadzhik593 - 07-31-2023
Please try this-
ALTER TABLE TABLE_NAME DROP INDEX `PRIMARY`, ADD PRIMARY KEY (COLUMN1, COLUMN2,..);