difference-between-unique-indexes-and-unique-constraints-in-sql-server 
SQL Shack
JUNE 10, 2020
This article gives you an overview of Unique Constraints in SQL and also the Unique SQL Server index. Along the way, we will look at the differences between them. Introduction Constraints in SQL Server allows defining the rules at the column level in the SQL table.
SQL Performance
MARCH 11, 2020
In the previous articles ( Part 1 , Part 2 , and Part 3 ), I covered the meaning of the NULL as a marker for a missing value, how NULLs behave in comparisons and in other query elements, and standard NULL handling features that are not yet available in T-SQL. Standard UNIQUE constraint. Unique constraint.
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SQL Performance
APRIL 13, 2022
However, these techniques require explicit sorting despite the presence of a supporting index. Finally, I’ll compare the performance of the different solutions. ( grp VARCHAR ( 10 ) NOT NULL , ord INT NOT NULL , val VARCHAR ( 10 ) NOT NULL , CONSTRAINT PK_T1 PRIMARY KEY ( grp , ord ) ) ; GO.
SQL Performance
SEPTEMBER 8, 2021
As part of the coverage, I’ll describe a curious inconsistency between how the CHECK OPTION in a view and a CHECK constraint in a table handle modifications—specifically ones involving NULLs. CONSTRAINT PK_Orders PRIMARY KEY , orderdate DATE NOT NULL , shippeddate DATE NULL. ) Sample Data. DROP TABLE IF EXISTS dbo.
SQL Performance
JANUARY 12, 2022
It so happens that the classic predicate-based technique for identifying interval intersection has poor performance since there's no good indexing scheme to support it. ( ID INT NOT NULL IDENTITY ( 1 , 1 ) CONSTRAINT pk_Auctions PRIMARY KEY CLUSTERED , Code CHAR ( 1 ) NOT NULL. DDL and a Small Set of Sample Data.
SQL Performance
JULY 13, 2022
The same goes specifically for handling T-SQL querying tasks in terms of supported language elements. T-SQL, the dialect, supports a subset of the features from standard SQL. This could also happen if you need to migrate code written for another database platform with a different dialect of SQL to T-SQL.
Percona
OCTOBER 18, 2023
It’s a complex process involving various factors and meticulous planning. Today, we’ll be taking a deep dive into the intricacies of database migration, along with specific solutions to help make the process easier. The savings can be particularly significant for organizations looking to optimize their IT spending.
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