Find Identity columns from another database - sql-server

Question

Normally with SQL Server you can use the COLUMNPROPERTY function like this to find the Identity columns in a database:
select TABLE_NAME + '.' + COLUMN_NAME, TABLE_NAME
from INFORMATION_SCHEMA.COLUMNS
where TABLE_SCHEMA = 'dbo'
and COLUMNPROPERTY(object_id(TABLE_NAME), COLUMN_NAME, 'IsIdentity') = 1
order by TABLE_NAME
But I can't figure out how to get this to work when running the query from another database. E.g. this does not return any results:
Use FirstDatabase
Go
select TABLE_NAME + '.' + COLUMN_NAME, TABLE_NAME
from SecondDatabase.INFORMATION_SCHEMA.COLUMNS
where TABLE_SCHEMA = 'dbo'
and COLUMNPROPERTY(object_id(TABLE_NAME), COLUMN_NAME, 'IsIdentity') = 1
order by TABLE_NAME

Answer 1

Object_ID only works in current db, unless you use a 3-part name, but that form is complicated to use. Also, ColumnProperty only works in current db.
select o.name + '.' + c.name, o.name
from test1.sys.columns c
join test1.sys.objects o on c.object_id = o.object_id
join test1.sys.schemas s on s.schema_id = o.schema_id
where s.name = 'dbo'
and o.is_ms_shipped = 0 and o.type = 'U'
and c.is_identity = 1
order by o.name

Answer 2

There is no way to get information with the help of COLUMNPROPERTY from another database. But there is on workaround:
DECLARE #DatabaseName VARCHAR(MAX)
DECLARE #TableName VARCHAR(MAX)
DECLARE #SQL VARCHAR(MAX)
SET #DatabaseName = 'MyDatabase'
SET #TableName = 'MyTable'
SET #SQL = '
SELECT
C.TABLE_NAME,
C.COLUMN_NAME,
S.IS_IDENTITY
FROM ' + #DatabaseName + '.INFORMATION_SCHEMA.COLUMNS AS C
LEFT JOIN ' + #DatabaseName + '.SYS.COLUMNS AS S ON OBJECT_ID(''' + #DatabaseName + '.dbo.' + #TableName + ''') = S.OBJECT_ID AND C.COLUMN_NAME = S.NAME
WHERE S.IS_IDENTITY = 1'
EXEC(#SQL)

Answer 3

This worked for me using a specific database:
USE <database_name>;
GO
SELECT SCHEMA_NAME(schema_id) AS schema_name
, t.name AS table_name
, c.name AS column_name
FROM sys.tables AS t
JOIN sys.identity_columns c ON t.object_id = c.object_id
ORDER BY schema_name, table_name;
GO

Answer 4

In this example, I've constructed a stored procedure in "Database1" that uses dynamic SQL to retrieve column information from a table in "Database2" (using the [INFORMATION_SCHEMA].[COLUMNS] system view residing in "Database2"):
ALTER PROCEDURE [Database1].[Schema1].[ColumnNames] #Database2 nvarchar(128), #Schema2 nvarchar(128), #Table2 nvarchar(128)
AS
BEGIN
DECLARE #Sql nvarchar(1000)
SET #Sql = 'SELECT [COLUMN_NAME], [ORDINAL_POSITION] FROM [' + #Database2 + '].[INFORMATION_SCHEMA].[COLUMNS]
WHERE [TABLE_SCHEMA] = ''' + #Schema2 + ''' AND [TABLE_NAME] = ''' + #Table2 + ''''
EXEC(#Sql)
END

Answer 5

I'm using SQL Server 2019, and I have run into the same challenge. I'm not sure if this fix will work for older versions, but there is a view in each DB called Your-DB-Name.sys.identity_columns. If you select from this view, you'll see the list of identity columns you have defined in that DB.
From that information you should be able to write a join connecting YourDBName.Information_schema.columns such as below:
SELECT *
FROM YourDBName.Information_Schema.columns col
LEFT OUTER JOIN YourDBName.sys.identity_columns idc
ON idc.name = col.COLUMN_NAME AND idc.object_id = object_id('YourDBName..YourTableName')
WHERE col.TABLE_NAME = 'YourTableName' AND col.table_catalog = 'YourDBName';
The YourDbName.sys.identity_columns view contains the following fields that might be useful:
object_id (used to join back to the table in question in case you have multiple tables with the same identity field name)
name (the name of the Identity field)
column_id (the order of the column in your table)
is_identity (tells you if this is an identity field)
seed_value (the initial value of the identity field)
increment_value (how much the identity field goes up with each insert)