Rename mixed-case tables in a single query - sql

Question

In my PostgreSQL 9.2 database there are many tables having name with mixed cases,For example
Tbl_Sales,Tbl_Purch,Tbl_logMnth
What I want to do is
alter table "Table1" rename to table1
but how to rename all mixed-case tables in my database in an easy way ?

Answer 1

this is the query to use
ALTER TABLE name
RENAME TO new_name

Answer 2

Use the following select to get the table(s) with mixed-cases in name
SELECT table_name ucase,lower(table_name) lcase
FROM information_schema.tables
where table_type = 'BASE TABLE' and
table_schema = 'public' and
table_name ~ E'^[[:upper:]][^[:upper:]]'
PostgreSQL string function lower and information_schema.tables
and use PL/PGSQL SQL - DO to rename all tables that have mixed-case
do
$$
declare
rw record;
begin
for rw in
SELECT 'ALTER TABLE "'||t.ucase||'" RENAME to '||t.lcase||';' execme from (
SELECT table_name ucase, lower(table_name) lcase
FROM information_schema.tables
where table_type = 'BASE TABLE' and
table_schema = 'public' and
table_name ~ E'^[[:upper:]][^[:upper:]]')t
loop
execute rw.execme ;
end loop;
end;
$$

Answer 3

Your best bet would probably be to generate a series of dynamic SQL statements, in, say, Python or similar by querying the pg_tables catalog.
You could then iterate over that list for the schemas in which you're interested (or all of them if you want to do that, so long as they're user-created -- you should avoid any of the pg_ ones, among others, as those are managed by Postgres itself) and check to see if the lowercase name is the same as the current name. If they are different, you can then generate the ALTER TABLE statement needed to rename the table, and then execute it, making sure to COMMIT your changes.
sqlfiddle with an example of this.
Note how the foo table I created is listed in there.
I'd recommend white-listing by schema, say, public and any others you want. In the fiddle, for example, you wouldn't want to touch anything in the pg_catalog nor information_schema schemas. You could also filter by tableowner -- you would probably want to avoid, for example, anything owned by the postgres user.
Also, note that when creating tables, casing doesn't matter. If a table foo already exists, and I then try to create Foo, the error ERROR: relation "foo" already exists will result.