Show table structure and list of tables in PostgreSQL [duplicate] - postgresql

Question

This question already has answers here:
PostgreSQL "DESCRIBE TABLE"
(24 answers)
Closed 6 years ago.
I had employed MySQL for a couple of former projects. But now have
decided to switch to PostgreSQL. Not that version 8 also works on that,
ahem other OS which I'm stuck with at work.
But alas, two of the most useful commands appear to be missing:
SHOW TABLES
DESCRIBE table
Inasmuch as my prototyping DB is on my NetBSD server at home while my
data waiting to be 'based is at work, such that I have to connect via
Perl/DBI and XML-RPC (not psql, alas). The IT dept here just says, "Use
MS-Access", so no help there.
While I'm in the initial stage I need an informative way to blunder
around and see what's what as I try different ways to build this thing.
For that I had always relied on the two above from MySQL.
I can't believe there is no way for PostgreSQL to tell me what the
current DB's table structure is via simple SQL queries executed remotely.
Surely there must be. But I can't seem to find out from the couple of
books I have. All I dug up was some ultra-lame hack to get column names
for an already known table name by doing a "WHERE 1 != 1" or some such
so that no actual rows could be returned. Not very informative, that.
Surely I've missed the point, somewhere.
So enlighten me, please. What, pray tell, are the PostgreSQL-ish SQL
queries one uses so as to explore a given DB's table structure? What is
the PostgreSQL translation for "SHOW TABLES" and "DESCRIBE table"?

Answer 1

SHOW TABLES and DESCRIBE TABLE are MySQL-specific admin commands, and nothing to do with standard SQL.
You want the:
\d
and
\d+ tablename
commands from psql.
These are implemented client-side. I find this odd myself, and would love to move them server-side as built-in SQL commands one day.
Other clients provide other ways to browse the structure - for example, PgAdmin-III.
If you want a portable way to get table structure in code, you should use the information_schema views, which are SQL-standard. See information_schema. They're available in MySQL, PostgreSQL, Ms-SQL, and most other DBs. The downside is that they're fiddlier to use, so they aren't convenient for quick access when you're just browsing a DB structure.

Answer 2

As per the Documentation
SELECT
table_schema || '.' || table_name as show_tables
FROM
information_schema.tables
WHERE
table_type = 'BASE TABLE'
AND
table_schema NOT IN ('pg_catalog', 'information_schema');
for more convenience make it as a function
create or replace function show_tables() returns SETOF text as $$
SELECT
table_schema || '.' || table_name as show_tables
FROM
information_schema.tables
WHERE
table_type = 'BASE TABLE'
AND
table_schema NOT IN ('pg_catalog', 'information_schema');
$$
language sql;
So we can get the tables using
select show_tables()
For the table description
select column_name, data_type, character_maximum_length
from INFORMATION_SCHEMA.COLUMNS where table_name ='table_name';
as a Function
create or replace function describe_table(tbl_name text) returns table(column_name
varchar, data_type varchar,character_maximum_length int) as $$
select column_name, data_type, character_maximum_length
from INFORMATION_SCHEMA.COLUMNS where table_name = $1;
$$
language 'sql';
select * from describe_table('a_table_name');