sys.dm_exec_describe_first_result_set (Transact-SQL)

Článek
05/16/2013

This dynamic management function takes a Transact-SQL statement as a parameter and describes the metadata of the first result set for the statement.

sys.dm_exec_describe_first_result_set has the same result set definition as sys.dm_exec_describe_first_result_set_for_object (Transact-SQL) and is similar to sp_describe_first_result_set (Transact-SQL).

Topic link icon Transact-SQL Syntax Conventions

Syntax

sys.dm_exec_describe_first_result(@tsql, @params, @include_browse_information)

Arguments

@tsql
One or more Transact-SQL statements. Transact-SQL_batch may be nvarchar(n) or nvarchar(max).
@params
@params provides a declaration string for parameters for the Transact-SQL batch, similar to sp_executesql. Parameters may be nvarchar(n) or nvarchar(max).

Is one string that contains the definitions of all parameters that have been embedded in the Transact-SQL_batch. The string must be either a Unicode constant or a Unicode variable. Each parameter definition consists of a parameter name and a data type. n is a placeholder that indicates additional parameter definitions. Every parameter specified in stmt must be defined in @params. If the Transact-SQL statement or batch in the statement does not contain parameters, @params is not required. NULL is the default value for this parameter.
@include\_browse\_information
If set to 1, each query is analyzed as if it has a FOR BROWSE option on the query. Additional key columns and source table information are returned.

Table Returned

This common metadata is returned as a result set. One row for each column in the results metadata describes the type and nullability of the column in the format shown in the following table. If the first statement does not exist for every control path, a result set with zero rows is returned.

Column name	Data type	Description
is_hidden	bit	Specifies that the column is an extra column added for browsing and informational purposes that does not actually appear in the result set.
column_ordinal	int	Contains the ordinal position of the column in the result set. Position of the first column will be specified as 1.
name	sysname	Contains the name of the column if a name can be determined. If not, will contain NULL.
is_nullable	bit	Contains the following values: Value 1 if column allows NULLs. Value 0 if the column does not allow NULLs. Value 1 if it cannot be determined that the column allows NULLs.
system_type_id	int	Contains the system_type_id of the column data type as specified in sys.types. For CLR types, even though the system_type_name column will return NULL, this column will return the value 240.
system_type_name	nvarchar(256)	Contains the name and arguments (such as length, precision, scale), specified for the data type of the column. If data type is a user-defined alias type, the underlying system type is specified here. If data type is a CLR user-defined type, NULL is returned in this column.
max_length	smallint	Maximum length (in bytes) of the column. -1 = Column data type is varchar(max), nvarchar(max), varbinary(max), or xml. For text columns, the max_length value will be 16 or the value set by sp_tableoption 'text in row'.
precision	tinyint	Precision of the column if numeric-based. Otherwise returns 0.
scale	tinyint	Scale of column if numeric-based. Otherwise returns 0.
collation_name	sysname	Name of the collation of the column if character-based. Otherwise returns NULL.
user_type_id	int	For CLR and alias types, contains the user_type_id of the data type of the column as specified in sys.types. Otherwise is NULL.
user_type_database	sysname	For CLR and alias types, contains the name of the database in which the type is defined. Otherwise is NULL.
user_type_schema	sysname	For CLR and alias types, contains the name of the schema in which the type is defined. Otherwise is NULL.
user_type_name	sysname	For CLR and alias types, contains the name of the type. Otherwise is NULL.
assembly_qualified_type_name	nvarchar(4000)	For CLR types, returns the name of the assembly and class defining the type. Otherwise is NULL.
xml_collection_id	int	Contains the xml_collection_id of the data type of the column as specified in sys.columns. This column returns NULL if the type returned is not associated with an XML schema collection.
xml_collection_database	sysname	Contains the database in which the XML schema collection associated with this type is defined. This column returns NULL if the type returned is not associated with an XML schema collection.
xml_collection_schema	sysname	Contains the schema in which the XML schema collection associated with this type is defined. This column returns NULL if the type returned is not associated with an XML schema collection.
xml_collection_name	sysname	Contains the name of the XML schema collection associated with this type. This column returns NULL if the type returned is not associated with an XML schema collection.
is_xml_document	bit	Returns 1 if the returned data type is XML and that type is guaranteed to be a complete XML document (including a root node), as opposed to an XML fragment). Otherwise returns 0.
is_case_sensitive	bit	Returns 1 if the column is of a case-sensitive string type. Returns 0 if it is not.
is_fixed_length_clr_type	bit	Returns 1 if the column is of a fixed-length CLR type. Returns 0 if it is not.
source_server	sysname	Name of the originating server (if it originates from a remote server). The name is given as it appears in sys.servers. Returns NULL if the column originates on the local server or if it cannot be determined which server it originates on. Is only populated if browsing information is requested.
source_database	sysname	Name of the originating database returned by the column in this result. Returns NULL if the database cannot be determined. Is only populated if browsing information is requested.
source_schema	sysname	Name of the originating schema returned by the column in this result. Returns NULL if the schema cannot be determined. Is only populated if browsing information is requested.
source_table	sysname	Name of the originating table returned by the column in this result. Returns NULL if the table cannot be determined. Is only populated if browsing information is requested.
source_column	sysname	Name of the originating column returned by the result column. Returns NULL if the column cannot be determined. Is only populated if browsing information is requested.
is_identity_column	bit	Returns 1 if the column is an identity column and 0 if not. Returns NULL if it cannot be determined that the column is an identity column.
is_part_of_unique_key	bit	Returns 1 if the column is part of a unique index (including unique and primary constraints) and 0 if it is not. Returns NULL if it cannot be determined that the column is part of a unique index. Is only populated if browsing information is requested.
is_updateable	bit	Returns 1 if the column is updateable and 0 if not. Returns NULL if it cannot be determined that the column is updateable.
is_computed_column	bit	Returns 1 if the column is a computed column and 0 if not. Returns NULL if it cannot be determined if the column is a computed column.
is_sparse_column_set	bit	Returns 1 if the column is a sparse column and 0 if not. Returns NULL if it cannot be determined that the column is a part of a sparse column set.
ordinal_in_order_by_list	smallint	ihe position of this column is in ORDER BY list. Returns NULL if the column does not appear in the ORDER BY list, or if the ORDER BY list cannot be uniquely determined.
order_by_list_length	smallint	The length of the ORDER BY list. NULL is returned if there is no ORDER BY list or if the ORDER BY list cannot be uniquely determined. Note that this value will be the same for all rows returned by sp_describe_first_result_set.
order_by_is_descending	smallint NULL	If the ordinal_in_order_by_list is not NULL, the order_by_is_descending column reports the direction of the ORDER BY clause for this column. Otherwise it reports NULL.
error_number	int	Contains the error number returned by the function. If no error occurred, the column will contain NULL.
error_severity	int	Contains the severity returned by the function. If no error occurred, the column will contain NULL.
error_state	int	Contains the state message. returned by the function. If no error occurred, the column will contain NULL.
error_message	nvarchar(4096)	Contains the message returned by the function. If no error occurred, the column will contain NULL.
error_type	int	Contains an integer representing the error being returned. Maps to error_type_desc. See the list under remarks.
error_type_desc	nvarchar(60)	Contains a short uppercase string representing the error being returned. Maps to error_type. See the list under remarks.

Remarks

This function uses the same algorithm as sp_describe_first_result_set. For more information, see sp_describe_first_result_set (Transact-SQL).

The following table lists the error types and their descriptions

error_type	error_type	Description
1	MISC	All errors that are not otherwise described.
2	SYNTAX	A syntax error occurred in the batch.
3	CONFLICTING_RESULTS	The result could not be determined because of a conflict between two possible first statements.
4	DYNAMIC_SQL	The result could not be determined because of dynamic SQL that could potentially return the first result.
5	CLR_PROCEDURE	The result could not be determined because a CLR stored procedure could potentially return the first result.
6	CLR_TRIGGER	The result could not be determined because a CLR trigger could potentially return the first result.
7	EXTENDED_PROCEDURE	The result could not be determined because an extended stored procedure could potentially return the first result.
8	UNDECLARED_PARAMETER	The result could not be determined because the data type of one or more of the result set’s columns potentially depends on an undeclared parameter.
9	RECURSION	The result could not be determined because the batch contains a recursive statement.
10	TEMPORARY_TABLE	The result could not be determined because the batch contains a temporary table and is not supported by sp_describe_first_result_set .
11	UNSUPPORTED_STATEMENT	The result could not be determined because the batch contains a statement that is not supported by sp_describe_first_result_set (e.g., FETCH, REVERT etc.).
12	OBJECT_TYPE_NOT_SUPPORTED	The @object_id passed to the function is not supported (i.e. not a stored procedure)
13	OBJECT_DOES_NOT_EXIST	The @object_id passed to the function was not found in the system catalog.

Permissions

Requires permission to execute the @tsql argument.

Examples

Additional examples in the topic sp_describe_first_result_set (Transact-SQL) can be adapted to use sys.dm_exec_describe_first_result_set.

A. Returning information about a single Transact-SQL statement

The following code returns information about the results of a Transact-SQL statement.

USE AdventureWorks2012;
GO
SELECT * FROM sys.dm_exec_describe_first_result_set
(N'SELECT object_id, name, type_desc FROM sys.indexes', null, 0) ;

B. Returning information about a procedure

The following example creates a stored procedure named pr_TestProc that returns two result sets. Then the example demonstrates that sys.dm_exec_describe_first_result_set returns information about the first result set in the procedure.

USE AdventureWorks2012;
GO

CREATE PROC Production.TestProc
AS
SELECT Name, ProductID, Color FROM Production.Product ;
SELECT Name, SafetyStockLevel, SellStartDate FROM Production.Product ;
GO

SELECT * FROM sys.dm_exec_describe_first_result_set
('Production.TestProc', NULL, 0) ;

C. Returning metadata from a batch that contains multiple statements

The following example evaluates a batch that contains two Transact-SQL statements. The result set describes the first result set returned.

USE AdventureWorks2012;
GO

SELECT * FROM sys.dm_exec_describe_first_result_set(
N'SELECT CustomerID, TerritoryID, AccountNumber FROM Sales.Customer WHERE CustomerID = @CustomerID;
SELECT * FROM Sales.SalesOrderHeader;',
N'@CustomerID int', 0) AS a;
GO

Sdílet prostřednictvím