constraints

Declarative SQL: Using UNIQUE Constraints

  • Article

In SQL, you can express the logic of what you want to accomplish without spelling out the details of how the database should do it. Nowhere is this more powerful than in constraints. In this introduction to Declarative SQL, Joe Celko demonstrates how you can write portable code that performs well and executes some complex logic, merely by creating unique constraints.

2015-12-15

6,149 reads

Set-based Constraint Violation Reporting in SQL Server

  • Article

When you're importing data into an RDBMS in bulk and an exception condition is raised because of a constraint violation, you generally need to fix the problem with the data and try again. The error won't tell you which rows are causing the violation. What if you've thousands of rows to search when it happens? There are solutions, writes William Sisson.

2014-10-16

8,821 reads

SQL Server Unique Constraints for Large Text Columns

  • Article

We are storing large text and URLs that are over 900 bytes in some of our tables and have a requirement to enforce uniqueness in those columns. But SQL Server has a limitation that index size can't be over 900 bytes. How do I enforce uniqueness in these columns and is it possible to achieve this in SQL Server 2005 and above? What are my different options to solve this problem? I heard that we can use CHECKSUM to create a hash, but is it possible to avoid collisions in the hash value as we are storing millions of rows?

2009-11-05

3,006 reads

Blogs

Power BI Monthly Digest – October 2019

By

In this month’s Power BI Digest with Manuel Quintana [Blog | Twitter] and I...

Database Fundamentals #24: Filtering Data

By

If you’ve been reading these Database Fundamentals posts, you’ve already seen the WHERE clause...

#PowershellBasics: The Windows Powershell icon in the task bar also lets you run Powershell ISE.

By

I don’t know about you, but I like having the tools that I’m likely...

Read the latest Blogs

Forums

More Network Restrictions

By Steve Jones - SSC Editor

Comments posted to this topic are about the item More Network Restrictions, which is...

Performance Tuning Question?

By CoolKid40

What are best steps to take to performance tune sql server?

Execution Plan vs Statistics I/0?

By CoolKid40

Whats difference between using execution plans vs statistics i/o to analyze and troubleshoot in...

Visit the forum

Ask SSC

SQL Server Q&A from the SQLServerCentral community

Get answers

Question of the Day

Another Typo

See possible answers