This article demonstrates how to use T-SQL to add a computed column to an existing table in SQL Server.
A computed column is a virtual column that uses an expression to calculate its value. The expression will typically use data from other columns. A computed column is not physically stored in the table unless it’s marked PERSISTED.
In SQL Server, a computed column is a virtual column that uses an expression to calculate its value.
A computed column will typically use data from other columns in its calculation. If data in any of those columns is updated, the computed column will automatically reflect the update in its calculation.
Continue readingThis article demonstrates how to use T-SQL to create a computed column in SQL Server.
A computed column is a virtual column that uses an expression to calculate its value. The expression will typically use data from other columns. A computed column is not physically stored in the table unless it’s marked PERSISTED.
In SQL Server, the @@MAX_CONNECTIONS configuration function returns the maximum number of simultaneous user connections allowed on an instance of SQL Server. The number returned is not necessarily the number currently configured.
No argument is required. You can simply use it in a SELECT statement to return the maximum number of simultaneous user connections allowed on the current server.
In SQL Server, the @@MAX_PRECISION configuration function returns the precision level used by decimal and numeric data types as currently set in the server.
No argument is required. You can simply use it in a SELECT statement to return the precision level of the current server.
Three of the system catalog views in SQL Server include sys.views, sys.system_views, and sys.all_views.
These three catalog views all provide metadata about views in the database, but there’s a subtle difference between each view.
If you’ve ever queried the sys.identity_columns view in SQL Server, you’ll know that it returns a list of identity columns. It also returns the object_id of the table, but not the table name or its schema.
You can use the code examples in this article to return the identity columns, along with their respective tables and schemas.
You can use T-SQL to return a list of identity columns in a database in SQL Server.
You can do this using the sys.identity_columns system catalog view.
You can use T-SQL to return a list of trigger events in a database in SQL Server.
You can do this using sys.trigger_events. This system catalog view returns a row for each event or event group on which a trigger can fire.
Here’s a hierarchical list of trigger event types that are returned in my SQL Server 2019 for Linux environment.
This list was created using this query.