Sql Server 2005 Function Execute Assignment

What is a function in SQL Server?

In SQL Server, a function is a stored program that you can pass parameters into and return a value.

Create Function

You can create your own functions in SQL Server (Transact-SQL). Let's take a closer look.

Syntax

The syntax to create a function in SQL Server (Transact-SQL) is:

CREATE FUNCTION [schema_name.]function_name ( [ @parameter [ AS ] [type_schema_name.] datatype [ = default ] [ READONLY ] , @parameter [ AS ] [type_schema_name.] datatype [ = default ] [ READONLY ] ] ) RETURNS return_datatype [ WITH { ENCRYPTION | SCHEMABINDING | RETURNS NULL ON NULL INPUT | CALLED ON NULL INPUT | EXECUTE AS Clause ] [ AS ] BEGIN [declaration_section] executable_section RETURN return_value END;
schema_name
The name of the schema that owns the function.
function_name
The name to assign to this function in SQL Server.
@parameter
One or more parameters passed into the function.
type_schema_name
The schema that owns the data type, if applicable.
datatype
The data type for @parameter.
default
The default value to assign to @parameter.
READONLY
It means that @parameter can not be overwritten by the function.
return_datatype
The datatype of the function's return value.
ENCRYPTION
It means that the source for the function will not be stored as plain text in the system views in SQL Server.
SCHEMABINDING
It means that the underlying objects can not be modified so as to affect the function.
RETURNS NULL ON NULL INPUT
It means that the function will return NULL if any parameters are NULL without having to execute the function.
CALL ON NULL INPUT
It means that the function will execute the function even if any parameters are NULL.
EXECUTE AS clause
Sets the security context to execute the function.
return_value
The value returned by the function.

Example

Let's look at an example of how to create a function in SQL Server (Transact-SQL).

The following is a simple example of a function:

CREATE FUNCTION ReturnSite ( @site_id INT ) RETURNS VARCHAR(50) AS BEGIN DECLARE @site_name VARCHAR(50); IF @site_id < 10 SET @site_name = 'TechOnTheNet.com'; ELSE SET @site_name = 'CheckYourMath.com'; RETURN @site_name; END;

This function is called ReturnSite. It has one parameter called @site_id which is an INT datatype. The function returns a VARCHAR(50) value, as specified by the RETURNS clause.

You could then reference the new function called ReturnSite as follows:

USE [test] GO SELECT dbo.ReturnSite(8); GO

Drop Function

Once you have created your function in SQL Server (Transact-SQL), you might find that you need to remove it from the database.

Syntax

The syntax to a drop a function in SQL Server (Transact-SQL) is:

DROP FUNCTION function_name;
function_name
The name of the function that you wish to drop.

Example

Let's look at an example of how to drop a function in SQL Server.

For example:

DROP FUNCTION ReturnSite;

This DROP FUNCTION example would drop the function called ReturnSite.

EXECUTE (Transact-SQL)

Executes a command string or character string within a Transact-SQL batch, or one of the following modules: system stored procedure, user-defined stored procedure, CLR stored procedure, scalar-valued user-defined function, or extended stored procedure. The EXECUTE statement can be used to send pass-through commands to linked servers. Additionally, the context in which a string or command is executed can be explicitly set. Metadata for the result set can be defined by using the WITH RESULT SETS options.

Important

Before you call EXECUTE with a character string, validate the character string. Never execute a command constructed from user input that has not been validated.

Transact-SQL Syntax Conventions

Syntax

Arguments

@return_status
Is an optional integer variable that stores the return status of a module. This variable must be declared in the batch, stored procedure, or function before it is used in an EXECUTE statement.

When used to invoke a scalar-valued user-defined function, the @return_status variable can be of any scalar data type.

module_name
Is the fully qualified or nonfully qualified name of the stored procedure or scalar-valued user-defined function to call. Module names must comply with the rules for identifiers. The names of extended stored procedures are always case-sensitive, regardless of the collation of the server.

A module that has been created in another database can be executed if the user running the module owns the module or has the appropriate permission to execute it in that database. A module can be executed on another server running SQL Server if the user running the module has the appropriate permission to use that server (remote access) and to execute the module in that database. If a server name is specified but no database name is specified, the SQL Server Database Engine looks for the module in the default database of the user.

;number
Applies to: SQL Server 2008 through SQL Server 2017

Is an optional integer that is used to group procedures of the same name. This parameter is not used for extended stored procedures.

Note

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.

For more information about procedure groups, see CREATE PROCEDURE (Transact-SQL).

@module_name_var
Is the name of a locally defined variable that represents a module name.

This can be a variable that holds the name of a natively compiled, scalar user-defined function.

@parameter
Is the parameter for module_name, as defined in the module. Parameter names must be preceded by the at sign (@). When used with the @parameter_name=value form, parameter names and constants do not have to be supplied in the order in which they are defined in the module. However, if the @parameter_name=value form is used for any parameter, it must be used for all subsequent parameters.

By default, parameters are nullable.

value
Is the value of the parameter to pass to the module or pass-through command. If parameter names are not specified, parameter values must be supplied in the order defined in the module.

When executing pass-through commands against linked servers, the order of the parameter values depends on the OLE DB provider of the linked server. Most OLE DB providers bind values to parameters from left to right.

If the value of a parameter is an object name, character string, or qualified by a database name or schema name, the whole name must be enclosed in single quotation marks. If the value of a parameter is a keyword, the keyword must be enclosed in double quotation marks.

If a default is defined in the module, a user can execute the module without specifying a parameter.

The default can also be NULL. Generally, the module definition specifies the action that should be taken if a parameter value is NULL.

@variable
Is the variable that stores a parameter or a return parameter.

OUTPUT
Specifies that the module or command string returns a parameter. The matching parameter in the module or command string must also have been created by using the keyword OUTPUT. Use this keyword when you use cursor variables as parameters.

If value is defined as OUTPUT of a module executed against a linked server, any changes to the corresponding @parameter performed by the OLE DB provider will be copied back to the variable at the end of the execution of module.

If OUTPUT parameters are being used and the intent is to use the return values in other statements within the calling batch or module, the value of the parameter must be passed as a variable, such as @parameter = @variable. You cannot execute a module by specifying OUTPUT for a parameter that is not defined as an OUTPUT parameter in the module. Constants cannot be passed to module by using OUTPUT; the return parameter requires a variable name. The data type of the variable must be declared and a value assigned before executing the procedure.

When EXECUTE is used against a remote stored procedure, or to execute a pass-through command against a linked server, OUTPUT parameters cannot be any one of the large object (LOB) data types.

Return parameters can be of any data type except the LOB data types.

DEFAULT
Supplies the default value of the parameter as defined in the module. When the module expects a value for a parameter that does not have a defined default and either a parameter is missing or the DEFAULT keyword is specified, an error occurs.

@string_variable
Is the name of a local variable. @string_variable can be any char, varchar, nchar, or nvarchar data type. These include the (max) data types.

84 'tsql_string'
Is a constant string. tsql_string can be any nvarchar or varchar data type. If the N is included, the string is interpreted as nvarchar data type.

AS <context_specification>
Specifies the context in which the statement is executed.

LOGIN
Applies to: SQL Server 2008 through SQL Server 2017

Specifies the context to be impersonated is a login. The scope of impersonation is the server.

USER
Specifies the context to be impersonated is a user in the current database. The scope of impersonation is restricted to the current database. A context switch to a database user does not inherit the server-level permissions of that user.

Important

While the context switch to the database user is active, any attempt to access resources outside the database will cause the statement to fail. This includes USE database statements, distributed queries, and queries that reference another database by using three- or four-part identifiers.

'name'
Is a valid user or login name. name must be a member of the sysadmin fixed server role or exist as a principal in sys.database_principals or sys.server_principals, respectively.

name cannot be a built-in account, such as NT AUTHORITY\LocalService, NT AUTHORITY\NetworkService, or NT AUTHORITY\LocalSystem.

For more information, see Specifying a User or Login Name later in this topic.

84 'command_string'
Is a constant string that contains the command to be passed through to the linked server. If the N is included, the string is interpreted as nvarchar data type.

[?]
Indicates parameters for which values are supplied in the <arg-list> of pass-through commands that are used in an EXEC('…', <arg-list>) AT <linkedsrv> statement.

AT linked_server_name
Applies to: SQL Server 2008 through SQL Server 2017

Specifies that command_string is executed against linked_server_name and results, if any, are returned to the client. linked_server_name must refer to an existing linked server definition in the local server. Linked servers are defined by using sp_addlinkedserver.

WITH <execute_option>
Possible execute options. The RESULT SETS options cannot be specified in an INSERT…EXEC statement.

TermDefinition
RECOMPILEForces a new plan to be compiled, used, and discarded after the module is executed. If there is an existing query plan for the module, this plan remains in the cache.

Use this option if the parameter you are supplying is atypical or if the data has significantly changed. This option is not used for extended stored procedures. We recommend that you use this option sparingly because it is expensive.

Note: You can not use WITH RECOMPILE when calling a stored procedure that uses OPENDATASOURCE syntax. The WITH RECOMPILE option is ignored when a four-part object name is specified.

Note: RECOMPILE is not supported with natively compiled, scalar user-defined functions. If you need to recompile, use sp_recompile (Transact-SQL).
RESULT SETS UNDEFINEDApplies to: SQL Server 2012 through SQL Server 2017, Azure SQL Database.

This option provides no guarantee of what results, if any, will be returned, and no definition is provided. The statement executes without error if any results are returned or no results are returned. RESULT SETS UNDEFINED is the default behavior if a result_sets_option is not provided.

For interpreted scalar user-defined functions, and natively compiled scalar user-defined functions, this option is not operational because the functions never return a result set.
RESULT SETS NONEApplies to: SQL Server 2012 through SQL Server 2017, Azure SQL Database.

Guarantees that the execute statement will not return any results. If any results are returned the batch is aborted.

For interpreted scalar user-defined functions, and natively compiled scalar user-defined functions, this option is not operational because the functions never return a result set.
<result_sets_definition>Applies to: SQL Server 2012 through SQL Server 2017, Azure SQL Database.

Provides a guarantee that the result will come back as specified in the result_sets_definition. For statements that return multiple result sets, provide multiple result_sets_definition sections. Enclose each result_sets_definition in parentheses, separated by commas. For more information, see <result_sets_definition> later in this topic.

This option always results in an error for natively compiled, scalar user-defined functions because the functions never return a result set.

<result_sets_definition> Applies to: SQL Server 2012 through SQL Server 2017, Azure SQL Database

Describes the result sets returned by the executed statements. The clauses of the result_sets_definition have the following meaning

TermDefinition
{

column_name

data_type

[ COLLATE collation_name]

[NULL | NOT NULL]

}
See the table below.
db_nameThe name of the database containing the table, view or table valued function.
schema_nameThe name of the schema owning the table, view or table valued function.
table_name | view_name | table_valued_function_nameSpecifies that the columns returned will be those specified in the table, view or table valued function named. Table variables, temporary tables, and synonyms are not supported in the AS object syntax.
AS TYPE [schema_name.]table_type_nameSpecifies that the columns returned will be those specified in the table type.
AS FOR XMLSpecifies that the XML results from the statement or stored procedure called by the EXECUTE statement will be converted into the format as though they were produced by a SELECT … FOR XML … statement. All formatting from the type directives in the original statement are removed, and the results returned are as though no type directive was specified. AS FOR XML does not convert non-XML tabular results from the executed statement or stored procedure into XML.
TermDefinition
column_nameThe names of each column. If the number of columns differs from the result set, an error occurs and the batch is aborted. If the name of a column differs from the result set, the column name returned will be set to the name defined.
data_typeThe data types of each column. If the data types differ, an implicit conversion to the defined data type is performed. If the conversion fails the batch is aborted
COLLATE collation_nameThe collation of each column. If there is a collation mismatch, an implicit collation is attempted. If that fails, the batch is aborted.
NULL | NOT NULLThe nullability of each column. If the defined nullability is NOT NULL and the data returned contains NULLs an error occurs and the batch is aborted. If not specified, the default value conforms to the setting of the ANSI_NULL_DFLT_ON and ANSI_NULL_DFLT_OFF options.

The actual result set being returned during execution can differ from the result defined using the WITH RESULT SETS clause in one of the following ways: number of result sets, number of columns, column name, nullability, and data type. If the number of result sets differs, an error occurs and the batch is aborted.

Parameters can be supplied either by using value or by using @parameter_name=value. A parameter is not part of a transaction; therefore, if a parameter is changed in a transaction that is later rolled back, the value of the parameter does not revert to its previous value. The value returned to the caller is always the value at the time the module returns.

Nesting occurs when one module calls another or executes managed code by referencing a common language runtime (CLR) module, user-defined type, or aggregate. The nesting level is incremented when the called module or managed code reference starts execution, and it is decremented when the called module or managed code reference has finished. Exceeding the maximum of 32 nesting levels causes the complete calling chain to fail. The current nesting level is stored in the @@NESTLEVEL system function.

Because remote stored procedures and extended stored procedures are not within the scope of a transaction (unless issued within a BEGIN DISTRIBUTED TRANSACTION statement or when used with various configuration options), commands executed through calls to them cannot be rolled back. For more information, see System Stored Procedures (Transact-SQL) and BEGIN DISTRIBUTED TRANSACTION (Transact-SQL).

When you use cursor variables, if you execute a procedure that passes in a cursor variable with a cursor allocated to it an error occurs.

You do not have to specify the EXECUTE keyword when executing modules if the statement is the first one in a batch.

For additional information specific to CLR stored procedures, see CLR Stored Procedures.

Using EXECUTE with Stored Procedures

You do not have to specify the EXECUTE keyword when you execute stored procedures when the statement is the first one in a batch.

SQL Server system stored procedures start with the characters sp_. They are physically stored in the Resource database, but logically appear in the sys schema of every system and user-defined database. When you execute a system stored procedure, either in a batch or inside a module such as a user-defined stored procedure or function, we recommend that you qualify the stored procedure name with the sys schema name.

SQL Server system extended stored procedures start with the characters xp_, and these are contained in the dbo schema of the master database. When you execute a system extended stored procedure, either in a batch or inside a module such as a user-defined stored procedure or function, we recommend that you qualify the stored procedure name with master.dbo.

When you execute a user-defined stored procedure, either in a batch or inside a module such as a user-defined stored procedure or function, we recommend that you qualify the stored procedure name with a schema name. We do not recommend that you name a user-defined stored procedure with the same name as a system stored procedure. For more information about executing stored procedures, see Execute a Stored Procedure.

Using EXECUTE with a Character String

In earlier versions of SQL Server, character strings are limited to 8,000 bytes. This requires concatenating large strings for dynamic execution. In SQL Server, the varchar(max) and nvarchar(max) data types can be specified that allow for character strings to be up to 2 gigabytes of data.

Changes in database context last only until the end of the EXECUTE statement. For example, after the in this following statement is run, the database context is master.

Context Switching

You can use the clause to switch the execution context of a dynamic statement. When the context switch is specified as , the duration of the context switch is limited to the scope of the query being executed.

Specifying a User or Login Name

The user or login name specified in must exist as a principal in sys.database_principals or sys.server_principals, respectively, or the statement will fail. Additionally, IMPERSONATE permissions must be granted on the principal. Unless the caller is the database owner or is a member of the sysadmin fixed server role, the principal must exist even when the user is accessing the database or instance of SQL Server through a Windows group membership. For example, assume the following conditions:

  • CompanyDomain\SQLUsers group has access to the Sales database.

  • CompanyDomain\SqlUser1 is a member of SQLUsers and, therefore, has implicit access to the Sales database.

    Although CompanyDomain\SqlUser1 has access to the database through membership in the SQLUsers group, the statement will fail because does not exist as a principal in the database.

Best Practices

Specify a login or user that has the least privileges required to perform the operations that are defined in the statement or module. For example, do not specify a login name, which has server-level permissions, if only database-level permissions are required; or do not specify a database owner account unless those permissions are required.

Permissions

Permissions are not required to run the EXECUTE statement. However, permissions are required on the securables that are referenced within the EXECUTE string. For example, if the string contains an INSERT statement, the caller of the EXECUTE statement must have INSERT permission on the target table. Permissions are checked at the time EXECUTE statement is encountered, even if the EXECUTE statement is included within a module.

EXECUTE permissions for a module default to the owner of the module, who can transfer them to other users. When a module is run that executes a string, permissions are checked in the context of the user who executes the module, not in the context of the user who created the module. However, if the same user owns the calling module and the module being called, EXECUTE permission checking is not performed for the second module.

If the module accesses other database objects, execution succeeds when you have EXECUTE permission on the module and one of the following is true:

  • The module is marked EXECUTE AS USER or SELF, and the module owner has the corresponding permissions on the referenced object. For more information about impersonation within a module, see EXECUTE AS Clause (Transact-SQL).

  • The module is marked EXECUTE AS CALLER, and you have the corresponding permissions on the object.

  • The module is marked EXECUTE AS user_name, and user_name has the corresponding permissions on the object.

Context Switching Permissions

To specify EXECUTE AS on a login, the caller must have IMPERSONATE permissions on the specified login name. To specify EXECUTE AS on a database user, the caller must have IMPERSONATE permissions on the specified user name. When no execution context is specified, or EXECUTE AS CALLER is specified, IMPERSONATE permissions are not required.

Examples

A. Using EXECUTE to pass a single parameter

The stored procedure in the AdventureWorks2012 database expects one parameter (). The following examples execute the stored procedure with as its parameter value.

The variable can be explicitly named in the execution:

If the following is the first statement in a batch or an osql or sqlcmd script, EXEC is not required.

B. Using multiple parameters

The following example executes the stored procedure in the AdventureWorks2012 database. It passes two parameters: the first parameter is a product ID () and the second parameter, is a value.

C. Using EXECUTE 'tsql_string' with a variable

The following example shows how handles dynamically built strings that contain variables. This example creates the cursor to hold a list of all user-defined tables in the AdventureWorks2012 database, and then uses that list to rebuild all indexes on the tables.

D. Using EXECUTE with a remote stored procedure

The following example executes the stored procedure on the remote server and stores the return status that indicates success or failure in .

Applies to: SQL Server 2008 through SQL Server 2017

E. Using EXECUTE with a stored procedure variable

The following example creates a variable that represents a stored procedure name.

F. Using EXECUTE with DEFAULT

The following example creates a stored procedure with default values for the first and third parameters. When the procedure is run, these defaults are inserted for the first and third parameters when no value is passed in the call or when the default is specified. Note the various ways the keyword can be used.

The stored procedure can be executed in many combinations.

G. Using EXECUTE with AT linked_server_name

The following example passes a command string to a remote server. It creates a linked server that points to another instance of SQL Server and executes a DDL statement () against that linked server.

Applies to: SQL Server 2008 through SQL Server 2017

H. Using EXECUTE WITH RECOMPILE

The following example executes the stored procedure and forces a new query plan to be compiled, used, and discarded after the module is executed.

I. Using EXECUTE with a user-defined function

The following example executes the scalar user-defined function in the AdventureWorks2012 database. It uses the variable to store the value returned by the function. The function expects one input parameter, . This is defined as a tinyint data type.

J. Using EXECUTE to query an Oracle database on a linked server

The following example executes several statements at the remote Oracle server. The example begins by adding the Oracle server as a linked server and creating linked server login.

Applies to: SQL Server 2008 through SQL Server 2017

K. Using EXECUTE AS USER to switch context to another user

The following example executes a Transact-SQL string that creates a table and specifies the clause to switch the execution context of the statement from the caller to . The Database Engine will check the permissions of when the statement is run. must exist as a user in the database and must have permission to create tables in the schema, or the statement fails.

L. Using a parameter with EXECUTE and AT linked_server_name

The following example passes a command string to a remote server by using a question mark () placeholder for a parameter. The example creates a linked server that points to another instance of SQL Server and executes a statement against that linked server. The statement uses the question mark as a place holder for the parameter (), which is provided after the statement.

Applies to: SQL Server 2008 through SQL Server 2017

M. Using EXECUTE to redefine a single result set

Some of the previous examples executed which returned 7 columns. The following example demonstrates using the syntax to change the names and data types of the returning result set.

Applies to: SQL Server 2012 through SQL Server 2017, Azure SQL Database

N. Using EXECUTE to redefine a two result sets

When executing a statement that returns more than one result set, define each expected result set. The following example in AdventureWorks2012 creates a procedure that returns two result sets. Then the procedure is executed using the WITH RESULT SETS clause, and specifying two result set definitions.

Applies to: SQL Server 2012 through SQL Server 2017, Azure SQL Database

Examples: Azure SQL Data Warehouse and Parallel Data Warehouse

Example O: Basic Procedure Execution

Executing a stored procedure:

Calling a stored procedure with name determined at runtime:

Calling a stored procedure from within a stored procedure:

Example P: Executing Strings

Executing a SQL string:

Executing a nested string:

Executing a string variable:

Example Q: Procedures with Parameters

The following example creates a procedure with parameters and demonstrates 3 ways to execute the procedure:

See Also

@@NESTLEVEL (Transact-SQL)
DECLARE @local_variable (Transact-SQL)
EXECUTE AS Clause (Transact-SQL)
osql Utility
Principals (Database Engine)
REVERT (Transact-SQL)
sp_addlinkedserver (Transact-SQL)
sqlcmd Utility
SUSER_NAME (Transact-SQL)
sys.database_principals (Transact-SQL)
sys.server_principals (Transact-SQL)
USER_NAME (Transact-SQL)
OPENDATASOURCE (Transact-SQL)
Scalar User-Defined Functions for In-Memory OLTP

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