Column, index, stored routine, and event names are not case-sensitive on any platform, nor are column aliases. However, names of logfile groups are case-sensitive. This differs from standard SQL. By default, table aliases are case-sensitive on Unix, but not so on Windows or macOS.
PostgreSQL is a case-sensitive database by default, but provides various possibilities for performing case-insensitive operations and working with collations.
SQL keywords are by default set to case insensitive that means that the keywords are allowed to be used in lower or upper case. The names of the tables and columns specification are set to case insensitive on the SQL database server, however, it can be enabled and disabled by configuring the settings in SQL.
The syntax to rename a column in a table in PostgreSQL (using the ALTER TABLE statement) is: ALTER TABLE table_name RENAME COLUMN old_name TO new_name; table_name. The name of the table to modify.
Identifiers (including column names) that are not double-quoted are folded to lowercase in PostgreSQL. Column names that were created with double-quotes and thereby retained uppercase letters (and/or other syntax violations) have to be double-quoted for the rest of their life:
"first_Name"
Values (string literals / constants) are enclosed in single quotes:
'xyz'
So, yes, PostgreSQL column names are case-sensitive (when double-quoted):
SELECT * FROM persons WHERE "first_Name" = 'xyz';
Read the manual on identifiers here.
My standing advice is to use legal, lower-case names exclusively so double-quoting is not needed.
To quote the documentation:
Key words and unquoted identifiers are case insensitive. Therefore:
UPDATE MY_TABLE SET A = 5;
can equivalently be written as:
uPDaTE my_TabLE SeT a = 5;
You could also write it using quoted identifiers:
UPDATE "my_table" SET "a" = 5;
Quoting an identifier makes it case-sensitive, whereas unquoted names are always folded to lower case (unlike the SQL standard where unquoted names are folded to upper case). For example, the identifiers FOO
, foo
, and "foo"
are considered the same by PostgreSQL, but "Foo"
and "FOO"
are different from these three and each other.
If you want to write portable applications you are advised to always quote a particular name or never quote it.
The column names which are mixed case or uppercase have to be double quoted in PostgresQL. So best convention will be to follow all small case with underscore.
if use JPA I recommend change to lowercase schema, table and column names, you can use next intructions for help you:
select
psat.schemaname,
psat.relname,
pa.attname,
psat.relid
from
pg_catalog.pg_stat_all_tables psat,
pg_catalog.pg_attribute pa
where
psat.relid = pa.attrelid
change schema name:
ALTER SCHEMA "XXXXX" RENAME TO xxxxx;
change table names:
ALTER TABLE xxxxx."AAAAA" RENAME TO aaaaa;
change column names:
ALTER TABLE xxxxx.aaaaa RENAME COLUMN "CCCCC" TO ccccc;
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