Binds a rule to a column or to an alias data type.
|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 CHECK constraints instead. CHECK constraints are created by using the CHECK keyword of the CREATE TABLE or ALTER TABLE statements.|
- [ @rulename =] 'rule'
Is the name of a rule created by the CREATE RULE statement. rule is nvarchar(776), with no default.
- [ @objname =] 'object_name'
Is the table and column, or the alias data type to which the rule is to be bound. A rule cannot be bound to a text, ntext, image, varchar(max), nvarchar(max), varbinary(max), xml, CLR user-defined type, or timestamp column. A rule cannot be bound to a computed column.
object_name is nvarchar(776), with no default. If object_name is a one-part name, it is resolved as an alias data type. If it is a two- or three-part name, it is first resolved as a table and column; and if this resolution fails, it is resolved as an alias data type. By default, existing columns of the alias data type inherit rule unless a rule has been bound directly to the column.
Note: object_name can contain the bracket [ and ] characters as delimited identifier characters. For more information, see Delimited Identifiers (Database Engine). Note: Rules created on expressions that use alias data types can be bound to columns or alias data types, but fail to compile when they are referenced. Avoid using rules created on alias data types.
- [ @futureonly = ] 'futureonly_flag'
Is used only when binding a rule to an alias data type. future_only_flag is varchar(15), with a default of NULL. This parameter when set to futureonly prevents existing columns of an alias data type from inheriting the new rule. If futureonly_flag is NULL, the new rule is bound to any columns of the alias data type that currently have no rule or that are using the existing rule of the alias data type.
You can bind a new rule to a column (although using a CHECK constraint is preferred) or to an alias data type with sp_bindrule without unbinding an existing rule. The old rule is overridden. If a rule is bound to a column with an existing CHECK constraint, all restrictions are evaluated. You cannot bind a rule to a SQL Server data type.
The rule is enforced when an INSERT statement is tried, not at binding. You can bind a character rule to a column of numeric data type, although such an INSERT operation is not valid.
Existing columns of the alias data type inherit the new rule unless futureonly_flag is specified as futureonly. New columns defined with the alias data type always inherit the rule. However, if the ALTER COLUMN clause of an ALTER TABLE statement changes the data type of a column to an alias data type bound to a rule, the rule bound to the data type is not inherited by the column. The rule must be specifically bound to the column by using sp_bindrule.
When you bind a rule to a column, related information is added to the sys.columns table. When you bind a rule to an alias data type, related information is added to the sys.types table.
A. Binding a rule to a column
Assuming that a rule named
today has been created in the current database by using the CREATE RULE statement, the following example binds the rule to the
HireDate column of the
Employee table. When a row is added to
Employee, the data for the
HireDate column is checked against the
USE master; GO EXEC sp_bindrule 'today', 'HumanResources.Employee.HireDate'
B. Binding a rule to an alias data type
Assuming the existence of a rule named
rule_ssn and an alias data type named
ssn, the following example binds
ssn. In a CREATE TABLE statement, columns of type
ssn inherit the
rule_ssn rule. Existing columns of type
ssn also inherit the
rule_ssn rule, unless futureonly is specified for futureonly_flag, or
ssn has a rule bound directly to it. Rules bound to columns always take precedence over those bound to data types.
USE master; GO EXEC sp_bindrule 'rule_ssn', 'ssn'
C. Using the futureonly_flag
The following example binds the
rule_ssn rule to the alias data type
futureonly is specified, no existing columns of type
ssn are affected.
USE master; GO EXEC sp_bindrule 'rule_ssn', 'ssn', 'futureonly'
D. Using delimited identifiers
The following example shows the use of delimited identifiers in object_name parameter.
USE master; GO CREATE TABLE [t.2] (c1 int) -- Notice the period as part of the table name. EXEC sp_bindrule rule1, '[t.2].c1' -- The object contains two periods; -- the first is part of the table name -- and the second distinguishes the table name from the column name.