Generate Primary Key Sql Server
14.12.2020 admin
As SQL Server DBAs we may need to generate a script for the creation of all Primary Keys, Unique and Foreign Key constraints. We know with the SQL Server native tools that there is not a way to meet this need all at the same time. In this tip we look at t. Learn how to define an auto increment primary key in SQL Server. This data tutorial will explain basic table creation and information around using identity a.
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Aug 05, 2019 This article demonstrates how to add a primary key to an existing table in SQL Server using Transact-SQL. A primary key is a column that has been configured as the unique identifier for a given table. You would normally create a primary key constraint when you create the table, but you can also add a primary key to an existing table. SQL PRIMARY KEY Constraint. The PRIMARY KEY constraint uniquely identifies each record in a table. Primary keys must contain UNIQUE values, and cannot contain NULL values. A table can have only ONE primary key; and in the table, this primary key can consist of single or multiple columns (fields). Summary: in this tutorial, you will learn how to use the SQL Server PRIMARY KEY constraint to create a primary key for a table. Introduction to SQL Server PRIMARY KEY constraint. A primary key is a column or a group of columns that uniquely identifies each row in a table. You create a primary key for a table by using the PRIMARY KEY constraint. If the primary key consists of only one column. Can't create table definition with primary key and SMO. 'Create the table on the instance of SQL Server. Tb.Create Dim idx As Index idx = New Index(tb, 'TestIndex') 'Add indexed columns to the index. Dim icol1 As IndexedColumn. Using SQL Server GUID as primary key. Sometimes, it prefers using GUID values for the primary key column of a table than using integers. Using GUID as the primary key of a table brings the following advantages: GUID values are globally unique across tables, databases, and even servers.
You can define a primary key in SQL Server by using SQL Server Management Studio or Transact-SQL. Creating a primary key automatically creates a corresponding unique clustered index, or a nonclustered index if specified as such.
Before You Begin
Limitations and Restrictions
A table can contain only one PRIMARY KEY constraint.
All columns defined within a PRIMARY KEY constraint must be defined as NOT NULL. If nullability is not specified, all columns participating in a PRIMARY KEY constraint have their nullability set to NOT NULL.
Security
Permissions
Creating a new table with a primary key requires CREATE TABLE permission in the database and ALTER permission on the schema in which the table is being created.
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Creating a primary key in an existing table requires ALTER permission on the table.
Using SQL Server Management Studio
To create a primary key
- In Object Explorer, right-click the table to which you want to add a unique constraint, and click Design.
- In Table Designer, click the row selector for the database column you want to define as the primary key. If you want to select multiple columns, hold down the CTRL key while you click the row selectors for the other columns.
- Right-click the row selector for the column and select Set Primary Key.
Caution
If you want to redefine the primary key, any relationships to the existing primary key must be deleted before the new primary key can be created. A message will warn you that existing relationships will be automatically deleted as part of this process.
A primary key column is identified by a primary key symbol in its row selector.
If a primary key consists of more than one column, duplicate values are allowed in one column, but each combination of values from all the columns in the primary key must be unique.
If you define a compound key, the order of columns in the primary key matches the order of columns as shown in the table. However, you can change the order of columns after the primary key is created. For more information, see Modify Primary Keys.
Using Transact-SQL
To create a primary key in an existing table
The following example creates a primary key on the column TransactionID in the AdventureWorks database.
To create a primary key in a new table
The following example creates a table and defines a primary key on the column TransactionID in the AdventureWorks database.
To create a primary key with clustered index in a new table
The following example creates a table and defines a primary key on the column CustomerID and a clustered index on TransactionID in the AdventureWorks database.
See Also
SQL PRIMARY KEY Constraint
The PRIMARY KEY constraint uniquely identifies each record in a table.
Proshow gold key generator free download. Primary keys must contain UNIQUE values, and cannot contain NULL values.
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A table can have only ONE primary key; and in the table, this primary key can consist of single or multiple columns (fields).
SQL PRIMARY KEY on CREATE TABLE
The following SQL creates a PRIMARY KEY on the 'ID' column when the 'Persons' table is created:
MySQL:
CREATE TABLE Persons (
ID int NOT NULL,
LastName varchar(255) NOT NULL,
FirstName varchar(255),
Age int,
PRIMARY KEY (ID)
);
ID int NOT NULL,
LastName varchar(255) NOT NULL,
FirstName varchar(255),
Age int,
PRIMARY KEY (ID)
);
SQL Server / Oracle / MS Access:
CREATE TABLE Persons (
ID int NOT NULL PRIMARY KEY,
LastName varchar(255) NOT NULL,
FirstName varchar(255),
Age int
);
ID int NOT NULL PRIMARY KEY,
LastName varchar(255) NOT NULL,
FirstName varchar(255),
Age int
);
To allow naming of a PRIMARY KEY constraint, and for defining a PRIMARY KEY constraint on multiple columns, use the following SQL syntax:
MySQL / SQL Server / Oracle / MS Access:
CREATE TABLE Persons (
ID int NOT NULL,
LastName varchar(255) NOT NULL,
FirstName varchar(255),
Age int,
CONSTRAINT PK_Person PRIMARY KEY (ID,LastName)
);
ID int NOT NULL,
LastName varchar(255) NOT NULL,
FirstName varchar(255),
Age int,
CONSTRAINT PK_Person PRIMARY KEY (ID,LastName)
);
Note: In the example above there is only ONE PRIMARY KEY (PK_Person). However, the VALUE of the primary key is made up of TWO COLUMNS (ID + LastName).
SQL PRIMARY KEY on ALTER TABLE
To create a PRIMARY KEY constraint on the 'ID' column when the table is already created, use the following SQL:
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MySQL / SQL Server / Oracle / MS Access:
To allow naming of a PRIMARY KEY constraint, and for defining a PRIMARY KEY constraint on multiple columns, use the following SQL syntax:
MySQL / SQL Server / Oracle / MS Access:
ALTER TABLE Persons
ADD CONSTRAINT PK_Person PRIMARY KEY (ID,LastName);
ADD CONSTRAINT PK_Person PRIMARY KEY (ID,LastName);
Note: If you use the ALTER TABLE statement to add a primary key, the primary key column(s) must already have been declared to not contain NULL values (when the table was first created).
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DROP a PRIMARY KEY Constraint
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To drop a PRIMARY KEY constraint, use the following SQL:
MySQL:
SQL Server / Oracle / MS Access: