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sys.columns (Transact-SQL)

  • Článek

Applies to: SQL Server Azure SQL Database Azure SQL Managed Instance Azure Synapse Analytics Analytics Platform System (PDW) SQL analytics endpoint in Microsoft Fabric Warehouse in Microsoft Fabric

Returns a row for each column of an object that has columns, such as views or tables. The following list contains the object types that have columns:

  • Table-valued assembly functions (FT)
  • Inline table-valued SQL functions (IF)
  • Internal tables (IT)
  • System tables (S)
  • Table-valued SQL functions (TF)
  • User tables (U)
  • Views (V)
Column name Data type Description
object_id int ID of the object to which this column belongs.
name sysname Name of the column. Is unique within the object.
column_id int ID of the column. Is unique within the object. Column IDs might not be sequential.
system_type_id tinyint ID of the system type of the column.
user_type_id int ID of the type of the column as defined by the user. To return the name of the type, join to the sys.types catalog view on 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, ntext, and image columns, the max_length value is 16 (representing the 16-byte pointer only) or the value set by sp_tableoption 'text in row'.
precision tinyint Precision of the column if numeric-based; otherwise, 0.
scale tinyint Scale of column if numeric-based; otherwise, 0.
collation_name sysname Name of the collation of the column if character-based; otherwise NULL.
is_nullable bit 1 = Column is nullable
0 = Column isn't nullable
is_ansi_padded bit 1 = Column uses ANSI_PADDING ON behavior if character, binary, or variant

0 = Column isn't character, binary, or variant
is_rowguidcol bit 1 = Column is a declared ROWGUIDCOL
is_identity bit 1 = Column has identity values
is_computed bit 1 = Column is a computed column
is_filestream bit 1 = Column is a FILESTREAM column
is_replicated bit 1 = Column is replicated
is_non_sql_subscribed bit 1 = Column has a non-SQL Server subscriber
is_merge_published bit 1 = Column is merge-published
is_dts_replicated bit 1 = Column is replicated by using SSIS
is_xml_document bit 1 = Content is a complete XML document

0 = Content is a document fragment, or the column data type isn't xml
xml_collection_id int Nonzero if the data type of the column is xml and the XML is typed. The value is the ID of the collection containing the validating XML schema namespace of the column

0 = No XML schema collection
default_object_id int ID of the default object, regardless of whether it's a stand-alone object sp_bindefault, or an inline, column-level DEFAULT constraint. The parent_object_id column of an inline column-level default object is a reference back to the table itself.

0 = No default
rule_object_id int ID of the stand-alone rule bound to the column by using sys.sp_bindrule.

0 = No stand-alone rule. For column-level CHECK constraints, see sys.check_constraints.
is_sparse bit 1 = Column is a sparse column. For more information, see Use sparse columns.
is_column_set bit 1 = Column is a column set. For more information, see Use sparse columns.
generated_always_type tinyint Identifies when the column value is generated (is always 0 for columns in system tables).

Applies to: SQL Server 2016 (13.x) and later versions, and SQL Database.

0 = NOT_APPLICABLE
1 = AS_ROW_START
2 = AS_ROW_END

Applies to: SQL Server 2022 (16.x) and later versions, and SQL Database.

5 = AS_TRANSACTION_ID_START
6 = AS_TRANSACTION_ID_END
7 = AS_SEQUENCE_NUMBER_START
8 = AS_SEQUENCE_NUMBER_END

For more information, see Temporal Tables (Relational databases).
generated_always_type_desc nvarchar(60) Textual description of the generated_always_type value (always NOT_APPLICABLE for columns in system tables)

Applies to: SQL Server 2016 (13.x) and later versions, and SQL Database.

NOT_APPLICABLE
AS_ROW_START
AS_ROW_END

Applies to: SQL Server 2022 (16.x) and later versions, and SQL Database.

AS_TRANSACTION_ID_START
AS_TRANSACTION_ID_END
AS_SEQUENCE_NUMBER_START
AS_SEQUENCE_NUMBER_END
encryption_type int Encryption type:

1 = Deterministic encryption
2 = Randomized encryption

Applies to: SQL Server 2016 (13.x) and later versions, and SQL Database
encryption_type_desc nvarchar(64) Encryption type description:

RANDOMIZED
DETERMINISTIC

Applies to: SQL Server 2016 (13.x) and later versions, and SQL Database
encryption_algorithm_name sysname Name of encryption algorithm. Only AEAD_AES_256_CBC_HMAC_SHA_512 is supported.

Applies to: SQL Server 2016 (13.x) and later versions, and SQL Database
column_encryption_key_id int ID of the column encryption key (CEK).

Applies to: SQL Server 2016 (13.x) and later versions, and SQL Database
column_encryption_key_database_name sysname The name of the database where the column encryption key exists if different than the database of the column. NULL if the key exists in the same database as the column.

Applies to: SQL Server 2016 (13.x) and later versions, and SQL Database
is_hidden bit Indicates if the column is hidden:

0 = regular, not-hidden, visible column
1 = hidden column

Applies to: SQL Server 2016 (13.x) and later versions, and SQL Database
is_masked bit Indicates if the column is masked by dynamic data masking:

0 = regular, not-masked column
1 = column is masked

Applies to: SQL Server 2016 (13.x) and later versions, and SQL Database
graph_type int Internal column with a set of values. The values are between 1 and 8 for graph columns, and NULL for others.
graph_type_desc nvarchar(60) Identified for informational purposes only. Not supported. Future compatibility is not guaranteed.
is_data_deletion_filter_column bit Indicates if the column is the data retention filter column for the table.

Applies to: Azure SQL Edge
ledger_view_column_type int If not NULL, indicates the type of a column in a ledger view:

1 = TRANSACTION_ID
2 = SEQUENCE_NUMBER
3 = OPERATION_TYPE
4 = OPERATION_TYPE_DESC

For more information, see Ledger overview.

Applies to: SQL Server 2022 (16.x) and later versions, and SQL Database
ledger_view_column_type_desc nvarchar(60) If not NULL, contains a textual description of the the type of a column in a ledger view:

TRANSACTION_ID
SEQUENCE_NUMBER
OPERATION_TYPE
OPERATION_TYPE_DESC

Applies to: SQL Server 2022 (16.x) and later versions, and SQL Database
is_dropped_ledger_column bit Indicates a ledger table column that was dropped.

Applies to: SQL Server 2022 (16.x) and later versions, and SQL Database

Permissions

The visibility of the metadata in catalog views is limited to securables that a user either owns, or on which the user was granted some permission. For more information, see Metadata Visibility Configuration.

Usage examples

Get column details for a table

To get metadata for columns in a table you can use the following code:

CREATE TABLE dbo.[sample] (
    id INT NOT NULL
    ,col1 VARBINARY(10) NULL
    )
GO

SELECT c.[name] AS column_name
    ,t.[name] AS [type_name]
    ,c.[max_length]
    ,c.[precision]
    ,c.[scale]
FROM sys.columns c
INNER JOIN sys.types t ON c.user_type_id = t.user_type_id
WHERE object_id = object_id('dbo.sample');

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