WebAug 15, 2006 · Answers. 0. Sign in to vote. If you are using SQL Server 2005, you can use the hashbytes function to compute say MD5 hash on the string and persist it in your table. You can then create unique constraint on that instead of the message_id. Also, this works only if the hash value is less than 900 bytes which should be the case for something like ... WebApr 27, 2024 · SQL Server Computed Column Overview. A Computed Column is a special type of columns with its values calculated using an expression that includes constant values, functions, data from other columns in the same table, or a combination of these components connected by one or more operators.
An Essential Guide to SQL Server Computed Columns By …
WebSQL Server must always ensure that the data in the index and base tables is synchronized, so we need to be careful when adding indexes to views. Every time an underlying column has a new row added or deleted, or is updated, SQL Server must maintain every clustered and non-clustered index, whether on the base table or the referenced indexed view. WebJun 1, 2024 · Only UNIQUE or PRIMARY KEY constraints can be created on computed columns, while CHECK, FOREIGN KEY, and NOT NULL constraints require that computed columns be persisted. In the following block of code, I will create a table to use for the first set of examples. 1 2 3 4 5 6 7 USE tempdb; GO CREATE TABLE MainTable ( MainTableId … burton cagen
Complex Computed Columns – SQLServerCentral
WebSep 10, 2024 · A computed column is a virtual column whose value is calculated from other values in the table. By default, the expression’s outputted value is not physically stored. Instead, SQL Server runs the expression when the column is queried and returns the value as part of the result set. WebOct 19, 2024 · sql server - Computed column cannot be persisted because the column is non-deterministic - Database Administrators Stack Exchange Computed column cannot be persisted because the column is non-deterministic Ask Question Asked 4 years, 5 months ago Modified 4 years, 5 months ago Viewed 16k times 14 WebJan 26, 2016 · T-SQL 22 Scalar functions in computed columns cause all queries that hit that table to execute serially. But it gets worse! Scalar functions in computed columns cause index maintenance to go single-threaded. If you’re running Expensive Edition, index rebuilds can be both online and parallel. burton of roots