[Operation and Maintenance|Database] How is COLLATE in MySQL represented in PostgreSQL?

In PostgreSQL, the concepts of character set (collation) and collation order (collation order) are similar to MySQL, but the syntax and usage are slightly different. In PostgreSQL, character set and collation are usually database, table or column level settings, rather than being specified in the query using the COLLATE keyword.

In PostgreSQL, you can set the character set and collation in the following ways:

1. Database level settings:
   When creating a database, you can specify a default character set and collation. For example:

CREATE DATABASE your_database
LC_COLLATE = 'your_collation'
LC_CTYPE = 'your_charset';

2. Table-level settings:
   When creating a table, you can specify a different collation for each column. For example:

CREATE TABLE your_table (
  column1 text COLLATE "your_collation",
  column2 text COLLATE "another_collation"
);

3. Column-level settings:
   You can also specify a default collation for the entire table when you create the table, and then specify the collation for specific columns in the query. For example:

CREATE TABLE your_table (
  column1 text,
  column2 text
) COLLATE "your_collation";

SELECT column2 FROM your_table ORDER BY column2 COLLATE "another_collation";

4. Query-level settings:
   In a query, you can use the COLLATE clause to specify collations for specific comparison operations. For example:

SELECT column1, column2
FROM your_table
WHERE column1 = 'value' COLLATE "your_collation";

Note that PostgreSQL uses the C (C-style) collation by default, which is fast but does not support multilingual collation. If you need to support different languages ​​or specific collation needs, you can select the appropriate character set and collation and set them at the database, table, or column level. This allows PostgreSQL to adapt to a variety of language and sorting needs.