How do I find a default constraint using INFORMATION_SCHEMA?
To locate a column's default constraint, use the following SQL query to combine the system catalog views and sys tables:
Replace 'YourTableName'
and 'YourColumnName'
to find the constraint name and definition for that specific column. You know, information_schema might be part of the ISO standard, but it unfortunately doesn't include default value constraints.
Why to prefer sys catalog views?
In SQL Server, default constraints are one of the few things the INFORMATION_SCHEMA
doesn't house. For these not-so-common guests, we need to knock the door of sys
catalog views.
Naming constraints: A game of names
Trust me, you'll thank yourself later for using a consistent naming convention for constraints. Makes life simpler when you plan any schema changes.
Operations on constraints: Setting them free
Need to modify or drop a constraint? Knowing the name of the default constraint is crucial. And sadly, INFORMATION_SCHEMA
doesn't offer this info on a silver platter. sys
views, however, do.
Sys views: Out with the old, in with the new
If you're still using deprecated system views (sysobjects
& syscolumns
) from SQL Server 2005 era, it's high time to migrate. Choose the robust catalog views in sys
for future compatibility & modern standards.
Working with old SQL Server versions
Running on MS SQL Server 2000? Unfortunately, sys
views aren't available here. In this case, consider INFORMATION_SCHEMA
or other alternatives, but remember, they come with their set of drawbacks.
What the future holds: Compatibility and standards
To ensure compatibility with the ever-evolving SQL Server, stick to the standard methods for searching constraints. sys
is today's standard, secure for your queries with default constraints.
Efficient if not elusive: Constraint tracing
When tracking constraint-related issues, efficient querying is as essential as a map for treasure hunt. Do not lean on INFORMATION_SCHEMA
for defaults. Bank on sys
view, your compass pointing to the right answers.
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