How do I list user defined types in a SQL Server d

问题:

I need to enumerate all the user defined types created in a SQL Server database with CREATE TYPE, and/or find out whether they have already been defined.

With tables or stored procedures I'd do something like this:

if exists (select * from dbo.sysobjects where name='foobar' and xtype='U')
    drop table foobar

However I can't find the equivalent (or a suitable alternative) for user defined types! I definitely can't see them anywhere in sysobjects.

Can anyone enlighten me?

回答1:

Types and UDTs don't appear in sys.objects. You should be able to get what you're looking for with the following:

select * from sys.types
where is_user_defined = 1

回答2:

Although the post is old, I found it useful to use a query similar to this. You may not find some of the formatting useful, but I wanted the fully qualified type name and I wanted to see the columns listed in order. You can just remove all of the SUBSTRING stuff to just get the column name by itself.

SELECT USER_NAME(TYPE.schema_id) + '.' + TYPE.name      AS "Type Name",
       COL.column_id,
       SUBSTRING(CAST(COL.column_id + 100 AS char(3)), 2, 2)  + ': ' + COL.name   AS "Column",
       ST.name                                          AS "Data Type",
       CASE COL.Is_Nullable
       WHEN 1 THEN ''
       ELSE        'NOT NULL' 
       END                                              AS "Nullable",
       COL.max_length                                   AS "Length",
       COL.[precision]                                  AS "Precision",
       COL.scale                                        AS "Scale",
       ST.collation                                     AS "Collation"
FROM sys.table_types TYPE
JOIN sys.columns     COL
    ON TYPE.type_table_object_id = COL.object_id
JOIN sys.systypes AS ST  
    ON ST.xtype = COL.system_type_id
where TYPE.is_user_defined = 1
ORDER BY "Type Name",
         COL.column_id

回答3:

To expand on jwolly2's answer, here's how you get a list of definitions including the standard data type:

-- User Defined Type definitions TP 20180124
select t1.name, t2.name, t1.precision, t1.scale, t1.max_length as bytes, t1.is_nullable
from sys.types t1
join sys.types t2 on t2.system_type_id = t1.system_type_id and t2.is_user_defined = 0
where t1.is_user_defined = 1 and t2.name <> 'sysname'
order by t1.name