Unfortunately, the database collation is quite limited in PostgreSQL it notably does not support non-deterministic collations (e.g. PostgreSQL also allows you to specify collations at the database level, when it is created: protected override void OnModelCreating(ModelBuilder modelBuilder) This will cause all textual operators on this column to be case-insensitive. ModelBuilder.Entity().Property(c => c.Name) ModelBuilder.HasCollation("my_collation", locale: "en-u-ks-primary", provider: "icu", deterministic: false) Once a collation has been created in your database, you can specify it on columns: protected override void OnModelCreating(ModelBuilder modelBuilder) Consult the ICU docs for more information on supported features and keywords. ICU collations are very powerful, and allow you to specify precise rules with regards to case, accents and other textual aspects. The rest of the parameters instruct PostgreSQL to create a non-deterministic, case-insensitive ICU collation. This creates a collation with the name my_collation: this is an arbitrary name you can choose, which you will be specifying later when assigning the collation to columns. To create a collation, place the following in your context's OnModelCreating: modelBuilder.HasCollation("my_collation", locale: "en-u-ks-primary", provider: "icu", deterministic: false) In PostgreSQL, collations are first-class, named database objects which can be created and dropped, just like tables. WHERE CASE WHEN x 0 THEN y/x > 1.It is not yet possible to use pattern matching operators such as LIKE on columns with a non-deterministic collation. For example, this is a possible way of avoiding a division-by-zero failure: The example above can be written using the simple CASE syntax:Ī CASE expression does not evaluate any subexpressions that are not needed to determine the result. This is similar to the switch statement in C. If no match is found, the result of the ELSE clause (or a null value) is returned. The first expression is computed, then compared to each of the value expressions in the WHEN clauses until one is found that is equal to it. There is a “ simple” form of CASE expression that is a variant of the general form above: The data types of all the result expressions must be convertible to a single output type. If the ELSE clause is omitted and no condition is true, the result is null. If no WHEN condition yields true, the value of the CASE expression is the result of the ELSE clause. If the condition's result is not true, any subsequent WHEN clauses are examined in the same manner. If the condition's result is true, the value of the CASE expression is the result that follows the condition, and the remainder of the CASE expression is not processed. Each condition is an expression that returns a boolean result. The SQL CASE expression is a generic conditional expression, similar to if/else statements in other programming languages:ĬASE clauses can be used wherever an expression is valid.
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