Understanding SQL Server Collation

Hello Dev, are you looking to broaden your knowledge about SQL Server Collation? Have you been wondering what SQL Server Collation is and what its possible impact is on your SQL Server database system? Then you have come to the right place. Today, we are going to explore SQL Server Collation and its role in your database system.

What is SQL Server Collation?

The SQL Server Collation defines the sort order, case sensitivity, and character encoding rules for storing non-Unicode data in SQL Server databases. It is a set of rules that determines how SQL Server compares and sorts the character data in your database. SQL Server 2000 and earlier versions were not flexible with collations and had limited options, but since SQL Server 2005, the number of available collations increased and provides more flexibility.

What is Collation Sequence?

Collation sequence is a series of rules that define how information is sorted and compared. For example, the sorting of the alphabet can be defined by a collation sequence. The collation sequence determines how characters are compared with each other using case sensitivity, accent sensitivity, and character width options.

In the next few paragraphs, we will be discussing various factors that you should consider when choosing your SQL Server collation; character set, case sensitivity, accent sensitivity, width sensitivity, and version compatibility.

Character Set

The character set is an important consideration when selecting a collation. SQL Server collations support Unicode (UTF-16) and non-Unicode (code page) character sets. The character set determines the supported characters and their encoding, affecting your application’s compatibility with databases. Choosing the right character encoding that supports your language and language-specific characters ensures that your data is stored and retrieved correctly.

Unicode or non-Unicode?

Unicode is a universal character set that supports almost all languages and scripts. Non-Unicode collations are specifically designed for character sets that use a single-byte encoding scheme. When dealing with data that uses characters in multiple code pages, Unicode collation is the way to go.

Case Sensitivity

Collation rules can also dictate whether case sensitivity is applied or not. Case-sensitive collations are designed to distinguish between uppercase and lowercase letters, while case-insensitive collations treat uppercase and lowercase letters the same.

Accent Sensitivity

Accent sensitivity determines whether or not accents are taken into account when sorting and comparing data. Some languages and scripts use accent marks, creating differences in the way words can be sorted. Accent-sensitive collations differentiate words with or without accents, while accent-insensitive collations treat them the same.

Width Sensitivity

Width sensitivity deals with how text data is sorted according to its width. Unicode characters can have different widths, such as single-byte or double-byte. Width-sensitive collations will differentiate between text with different widths, while width-insensitive collations will not.

Version Compatibility

Choosing a collation that is not supported in your current SQL Server version may cause compatibility issues. Some collations are deprecated in newer versions, while others may not be supported at all. It is important to choose a collation that is compatible with your SQL Server version.

Understanding Collation Precedence

SQL Server collations have a hierarchy of precedence when comparing and sorting data. The following table shows the order of precedence for some of the most commonly used collations:

Collation	Precedence
SQL_Latin1_General_CP1_CI_AS	1
Latin1_General_CI_AS	2
Latin1_General_CI_AI	3

In this table, SQL_Latin1_General_CP1_CI_AS has the highest precedence and Latin1_General_CI_AI has the lowest. If two values are compared with different collations, the collation with the higher precedence will be used.

FAQs About SQL Server Collation

What is the default collation of SQL Server?

The default collation for SQL Server is SQL_Latin1_General_CP1_CI_AS.

Can I change the collation of a SQL Server database?

Yes, you can change the collation of your entire SQL Server database or specific columns, tables, or even a single query. To change the collation of a database or object, use the ALTER DATABASE or ALTER TABLE statements, respectively.

What are the implications of changing a database’s collation?

Changing collation can be a complex process and may affect existing data, queries, and applications. Changing collation may result in data corruption, data loss, or incorrect sorting and searching.

Can I use different collations for different columns in the same table?

Yes, you can use different collations for different columns within the same table. This can be done by specifying the collation for each column when creating the table or altering the table.

What is the best collation to use?

The best collation to use depends on the requirements of your application and the languages and scripts it supports. Some languages and scripts require specific collations, while others may benefit from case-insensitive or accent-insensitive collations. When in doubt, consult the Microsoft documentation or seek advice from a SQL Server expert.

In Conclusion

SQL Server Collation is an essential part of your database system. Choosing the right collation sequence will ensure that your data is sorted and compared correctly, making it easier to retrieve and analyze. Understanding the character set, case sensitivity, accent sensitivity, width sensitivity, and version compatibility are crucial in determining which collation to use. Remember to select a collation that matches the language and language-specific characters of your data, and ensure that it is compatible with your SQL Server version.