sp_addtype (Transact-SQL)

مقالة
05/16/2013

Creates an alias data type.

Important

This feature will be removed in a future version of Microsoft SQL Server. Avoid using this feature in new development work, and plan to modify applications that currently use this feature. Use CREATE TYPE instead.

Topic link icon Transact-SQL Syntax Conventions

Syntax

sp_addtype [ @typename = ] type, 
    [ @phystype = ] system_data_type 
    [ , [ @nulltype = ] 'null_type' ] ;

Arguments

[ @typename= ] type
Is the name of the alias data type. Alias data type names must follow the rules for identifiers and must be unique in each database. type is sysname, with no default.

[ @phystype=] system_data_type
Is the physical, or SQL Server supplied, data type on which the alias data type is based.system_data_type is sysname, with no default, and can be one of these values:

bigint	binary(n)	bit
char(n)	datetime	decimal
float	image	int
money	nchar(n)	ntext
numeric	nvarchar(n)	real
smalldatetime	smallint	smallmoney
sql_variant	text	tinyint
uniqueidentifier	varbinary(n)	varchar(n)

Quotation marks are required around all parameters that have embedded blank spaces or punctuation marks. For more information about available data types, see Data Types (Transact-SQL).

n
Is a nonnegative integer that indicates the length for the chosen data type.
P
Is a nonnegative integer that indicates the maximum total number of decimal digits that can be stored, both to the left and to the right of the decimal point. For more information, see decimal and numeric (Transact-SQL).
s
Is a nonnegative integer that indicates the maximum number of decimal digits that can be stored to the right of the decimal point, and it must be less than or equal to the precision. For more information, see decimal and numeric (Transact-SQL).
[ @nulltype = ] 'null_type'
Indicates the way the alias data type handles null values. null_type is varchar(8), with a default of NULL, and must be enclosed in single quotation marks ('NULL', 'NOT NULL', or 'NONULL'). If null_type is not explicitly defined by sp_addtype, it is set to the current default nullability. Use the GETANSINULL system function to determine the current default nullability. This can be adjusted by using the SET statement or ALTER DATABASE. Nullability should be explicitly defined. If @phystype is bit, and @nulltype is not specified, the default is NOT NULL.

Note

The null_type parameter only defines the default nullability for this data type. If nullability is explicitly defined when the alias data type is used during table creation, it takes precedence over the defined nullability. For more information, see ALTER TABLE (Transact-SQL) and CREATE TABLE (Transact-SQL).

Return Code Values

0 (success) or 1 (failure)

Result Sets

None

Remarks

An alias data type name must be unique in the database, but alias data types with different names can have the same definition.

Executing sp_addtype creates an alias data type that appears in the sys.types catalog view for a specific database. If the alias data type must be available in all new user-defined databases, add it to model. After an alias data type is created, you can use it in CREATE TABLE or ALTER TABLE, and also bind defaults and rules to the alias data type. All scalar alias data types that are created by using sp_addtype are contained in the dbo schema.

Alias data types inherit the default collation of the database. The collations of columns and variables of alias types are defined in the Transact-SQL CREATE TABLE, ALTER TABLE and DECLARE @local\_variable statements. Changing the default collation of the database applies only to new columns and variables of the type; it does not change the collation of existing ones.

Security Note
For backward compatibility purposes, the public database role is automatically granted REFERENCES permission on alias data types that are created by using sp_addtype. Note when alias data types are created by using the CREATE TYPE statement instead of sp_addtype, no such automatic grant occurs.

Alias data types cannot be defined by using the SQL Server timestamp, table, xml, varchar(max), nvarchar(max) or varbinary(max) data types.

Permissions

Requires membership in the db_owner or db_ddladmin fixed database role.

Examples

A. Creating an alias data type that does not allow for null values

The following example creates an alias data type named ssn (social security number) that is based on the SQL Server-supplied varchar data type. The ssn data type is used for columns holding 11-digit social security numbers (999-99-9999). The column cannot be NULL.

Notice that varchar(11) is enclosed in single quotation marks because it contains punctuation (parentheses).

USE master;
GO
EXEC sp_addtype ssn, 'varchar(11)', 'NOT NULL';
GO

B. Creating an alias data type that allows for null values

The following example creates an alias data type (based on datetime) named birthday that allows for null values.

USE master;
GO
EXEC sp_addtype birthday, datetime, 'NULL';

C. Creating additional alias data types

The following example creates two additional alias data types, telephone and fax, for both domestic and international telephone and fax numbers.

USE master;
GO
EXEC sp_addtype telephone, 'varchar(24)', 'NOT NULL';
GO
EXEC sp_addtype fax, 'varchar(24)', 'NULL';
GO

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