SQL Server 2005+ - Get All Default and Check Constraints - sql

Question

I have the following query (put on my dba hat today :)) and I was wondering if anyone knows of a better way to get the Default And Check constraints without a Union All. This would sure make adding a where clause easier and more efficient.
SELECT
t.Name AS [TableName],
SCHEMA_NAME(t.schema_id) AS [SchemaName],
c.Name AS [ColumnName],
dc.Name AS ConstraintName,
'DEFAULT' AS ConstraintType,
dc.definition AS ConstraintDef
FROM sys.tables t
INNER JOIN sys.default_constraints dc ON t.object_id = dc.parent_object_id
INNER JOIN sys.columns c ON dc.parent_object_id = c.object_id AND c.column_id = dc.parent_column_id
UNION ALL
SELECT
t.Name AS [TableName],
SCHEMA_NAME(t.schema_id) AS [SchemaName],
c.Name AS [ColumnName],
cc.Name AS ConstraintName,
'CHECK' AS ConstraintType,
cc.definition AS ConstraintDef
FROM sys.tables t
INNER JOIN sys.check_constraints cc ON t.object_id = cc.parent_object_id
INNER JOIN sys.columns c ON cc.parent_object_id = c.object_id AND c.column_id = cc.parent_column_id
Please note that this needs to work on SQL Server 2005+ as well as azure. The current script works but doesn't work efficiently when I need to add a where clause dynamically to limit the results.

Answer 1

You can reduce the total amount of JOINs for example like this:
with constraints as (
select parent_object_id, parent_column_id, name, definition,
'DEFAULT' [ConstraintType]
from sys.default_constraints
union all
select parent_object_id, parent_column_id, name, definition, 'CHECK'
from sys.check_constraints
)
SELECT
t.Name AS [TableName],
SCHEMA_NAME(t.schema_id) AS [SchemaName],
c.Name AS [ColumnName],
dc.Name AS ConstraintName,
dc.ConstraintType,
dc.definition AS ConstraintDef
FROM sys.tables t
INNER JOIN constraints dc ON t.object_id = dc.parent_object_id
INNER JOIN sys.columns c ON dc.parent_object_id = c.object_id
AND c.column_id = dc.parent_column_id
or you can use another approach (using sys.sysconstraints and sys.objects)
SELECT
t.Name AS [TableName],
SCHEMA_NAME(t.schema_id) AS [SchemaName],
c.Name AS [ColumnName],
dc.Name AS ConstraintName,
dc.ConstraintType,
dc.definition AS ConstraintDef
FROM sys.tables t
INNER JOIN (
SELECT object_definition(o.object_id) [definition], OBJECT_NAME(o.OBJECT_ID) [Name],
o.parent_object_id, o.type_desc [ConstraintType], c.colid [parent_column_id]
FROM sys.objects o
join sys.sysconstraints c on o.object_id = c.constid
WHERE type_desc in ('DEFAULT_CONSTRAINT', 'CHECK_CONSTRAINT')
) dc ON t.object_id = dc.parent_object_id
INNER JOIN sys.columns c ON dc.parent_object_id = c.object_id
AND c.column_id = dc.parent_column_id