11/26/2023 0 Comments Sqlite regex case insensitive![]() Indexes are one of the most important factors in database performance - a query that runs efficiently with an index can grind to a halt without that index. COLLATE SQL_Latin1_General_CP1_CS_AS = N'John' This generates a COLLATE clause in the SQL query, which applies a case-sensitive collation regardless of the collation defined at the column or database level: SELECT. Where(c => EF.Functions.Collate(c.Name, "SQL_Latin1_General_CP1_CS_AS") = "John") This can be accomplished by explicitly specifying a collation within the query itself: var customers = context.Customers For example, one query may need to perform a case-sensitive comparison on a column, while another may need to perform a case-insensitive comparison on the same column. ![]() In some cases, the same column needs to be queried using different collations by different queries. UseCollation("SQL_Latin1_General_CP1_CI_AS") When using EF Core migrations to manage your database schema, the following configures the column for the Name property to be case-insensitive in a database that is otherwise configured to be case-sensitive: modelBuilder.Entity().Property(c => c.Name) This can be useful if certain columns need to be case-insensitive, while the rest of the database needs to be case-sensitive. When using EF Core migrations to manage your database schema, the following in your model's OnModelCreating method configures a SQL Server database to use a case-sensitive collation: modelBuilder.UseCollation("SQL_Latin1_General_CP1_CS_AS") Ĭollations can also be defined on text columns, overriding the database default. Although database systems usually do permit altering the collation of an existing database, doing so can lead to complications it is recommended to pick a collation before database creation. For example, the default server-level collation in SQL Server for the "English (United States)" machine locale is SQL_Latin1_General_CP1_CI_AS, which is a case-insensitive, accent-sensitive collation. The database collation is typically set at database creation time (via the CREATE DATABASE DDL statement), and if not specified, defaults to a some server-level value determined at setup time. In most database systems, a default collation is defined at the database level unless overridden, that collation implicitly applies to all text operations occurring within that database. ![]() Fortunately, databases do generally allow a default collation to be defined at the database or column level, and to explicitly specify which collation should be used for specific operations in a query. The actual list of available collations and their naming schemes is database-specific consult the section below for links to relevant documentation pages of various databases. Finally, collations also define how text values are ordered: while German places ä after a, Swedish places it at the end of the alphabet.Īll text operations in a database use a collation - whether explicitly or implicitly - to determine how the operation compares and orders strings. The scope of collations also extends beyond case-sensitivity, to other aspects of character data in German, for example, it is sometimes (but not always) desirable to treat ä and ae as identical. i and I represent different letters in Turkish), there exist multiple case-insensitive collations, each with its own set of rules. However, since case-sensitivity is culture-sensitive (e.g. For example, while a case-insensitive collation disregards differences between upper- and lower-case letters for the purposes of equality comparison, a case-sensitive collation does not. ![]() Introduction to collationsĪ fundamental concept in text processing is the collation, which is a set of rules determining how text values are ordered and compared for equality. This page details how to configure case sensitivity, or more generally, collations, and how to do so in an efficient way without compromising query performance. In addition, because of index usage, case-sensitivity and similar aspects can have a far-reaching impact on query performance: while it may be tempting to use string.ToLower to force a case-insensitive comparison in a case-sensitive database, doing so may prevent your application from using indexes. Sqlite, PostgreSQL), others are case-insensitive (SQL Server, MySQL). For one thing, databases vary considerably in how they handle text for example, while some databases are case-sensitive by default (e.g. ![]() Text processing in databases can be complex, and requires more user attention than one would suspect. ![]()
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