Reputation: 4102
I have a db table say, persons
in Postgres handed down by another team that has a column name say, "first_Name"
. Now am trying to use PG commander to query this table on this column-name.
select * from persons where first_Name="xyz";
And it just returns
ERROR: column "first_Name" does not exist
Not sure if I am doing something silly or is there a workaround to this problem that I am missing?
Upvotes: 273
Views: 246321
Reputation: 1457
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.
Example:
create table mytable (a int, "B" int);
select a from mytable; -- works
select "a" from mytable; -- also works
select "B" from mytable; -- works
select b from mytable; -- ERROR: column "b" does not exist
select "b" from mytable; -- ERROR: column "b" does not exist
As you can see, if the column contains an upper-case character, it must always be quoted when referencing it.
Tested with PostgreSQL 17.
Upvotes: 20
Reputation: 658757
Identifiers (including column names) that are not double-quoted are folded to lower case in PostgreSQL. Identifiers created with double quotes retain upper case letters (and/or syntax violations) and have to be double-quoted for the rest of their life:
"first_Name" -- upper-case "N" preserved
"1st_Name" -- leading digit preserved
"AND" -- reserved word preserved
But (without double-quotes):
first_Name → first_name -- upper-case "N" folded to lower-case "n"
1st_Name → Syntax error! -- leading digit
AND → Syntax error! -- reserved word
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';
My standing advice is to use legal, lower-case names exclusively, so double-quoting is never required.
System catalogs like pg_class
store names in case-sensitive fashion - as provided when double-quoted (without enclosing quotes, obviously), or lower-cased if not.
Upvotes: 504
Reputation: 205
You can try this example for table and column naming in capital letters. (postgresql)
//Sql;
create table "Test"
(
"ID" integer,
"NAME" varchar(255)
)
//C#
string sqlCommand = $@"create table ""TestTable"" (
""ID"" integer GENERATED BY DEFAULT AS IDENTITY primary key,
""ExampleProperty"" boolean,
""ColumnName"" varchar(255))";
Upvotes: 1
Reputation: 51
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;
Upvotes: 5
Reputation: 150109
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.
Upvotes: 29