How to create composite primary key in SQL Server 2008

Question

I want to create tables in SQL Server 2008  but I don t know how to create composite primary key  How can I achieve this

User · Answer

For MSSQL Server 2012  CREATE TABLE usrgroup    usr id int FOREIGN KEY REFERENCES users id     grp id int FOREIGN KEY REFERENCES groups id      PRIMARY KEY  usr id  grp id      UPDATE  I should add    If you want to add foreign   primary keys altering  firstly you should create the keys with constraints or you can not make changes  Like this below   CREATE TABLE usrgroup    usr id int    grp id int     CONSTRAINT FK usrgroup usrid FOREIGN KEY  usr id  REFERENCES users id     CONSTRAINT FK usrgroup groupid FOREIGN KEY  grp id  REFERENCES groups id      CONSTRAINT PK usrgroup PRIMARY KEY  usr id grp id      Actually last way is healthier and serial  You can look the FK PK Constraint names  dbo dbname   Keys       but if you do not use a constraint  MSSQL auto-creates random FK PK names  You will need to look at every change  alter table  you need    I recommend that you set a standard for yourself  the constraint should be defined according to the your standard  You will not have to memorize and you will not have to think too long  In short  you work faster

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First create the database and table  manually adding the columns  In which column to be primary key  You should right click this column and set primary key and set the seed value of the primary key

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create table my table        column a integer not null       column b integer not null       column c varchar 50        primary key  column a  column b

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To create a composite unique key on table   ALTER TABLE  TableName  ADD UNIQUE   Column1    Column2    column3

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CREATE TABLE UserGroup      User Id  INT NOT NULL     Group Id  INT NOT NULL    CONSTRAINT PK UserGroup PRIMARY KEY NONCLUSTERED   User Id    Group Id

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Via Enterprise Manager  SSMS       Right Click on the Table you wish to create the composite key on and select Design  Highlight the columns you wish to form as a composite key Right Click over those columns and Set Primary Key   To see the SQL you can then right click on the Table   Script Table As   Create To

User · Answer

I know I m late to this party  but for an existing table  try   ALTER table TABLE NAME ADD CONSTRAINT  name of your PK  e g  PK TableName  PRIMARY KEY CLUSTERED  column1  column2  etc

User · Answer

CREATE TABLE UserGroup      User Id  INT Foreign Key     Group Id  INT foreign key    PRIMARY KEY   User Id    Group Id

[sql] How to create composite primary key in SQL Server 2008

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