PostgreSQL Rename

Rename command is used to rename a table. Following is its Syntax,
Syntax:

ALTER TABLE [ ONLY ] name [ * ]
    action [, ... ]
ALTER TABLE [ ONLY ] name [ * ]
    RENAME [ COLUMN ] column TO new_column
ALTER TABLE name
    RENAME TO new_name
ALTER TABLE name
    SET SCHEMA new_schema

rename table old-table-name to new-table-name
Here is an Example explaining it.

postgres=# \dt
          List of relations
 Schema |   Name   | Type  |  Owner   
--------+----------+-------+----------
 benz2  | dept     | table | postgres
 benz2  | item     | table | u2
 benz2  | products | table | u2
 benz2  | t1       | table | u7
 benz2  | t10      | table | u3
 benz2  | t11      | table | u5
 benz2  | t6       | table | u2
 benz2  | t9       | table | u2
(8 rows)


postgres=# alter table t9 rename to t9_RENAMED;
ALTER TABLE

postgres=# \dt                                 
           List of relations
 Schema |    Name    | Type  |  Owner   
--------+------------+-------+----------
 benz2  | dept       | table | postgres
 benz2  | item       | table | u2
 benz2  | products   | table | u2
 benz2  | t1         | table | u7
 benz2  | t10        | table | u3
 benz2  | t11        | table | u5
 benz2  | t6         | table | u2
 benz2  | t9_renamed | table | u2
(8 rows)postgres=# \dt

The above query will rename t9 table to t9_renamed.

Here I gave some more example starting Listener some of the example you will not understand that's not a matter Just gothrough untill what your untderstanding
Examples
To add a column of type varchar to a table:

ALTER TABLE distributors ADD COLUMN address varchar(30);

To drop a column from a table:

ALTER TABLE distributors DROP COLUMN address RESTRICT;

To change the types of two existing columns in one operation:

ALTER TABLE distributors

    ALTER COLUMN address TYPE varchar(80),

    ALTER COLUMN name TYPE varchar(100);

To change an integer column containing UNIX timestamps to timestamp with time zone via a USING clause:

ALTER TABLE foo

    ALTER COLUMN foo_timestamp SET DATA TYPE timestamp with time zone

    USING

        timestamp with time zone 'epoch' + foo_timestamp * interval '1 second';

The same, when the column has a default expression that won't automatically cast to the new data type:

ALTER TABLE foo

    ALTER COLUMN foo_timestamp DROP DEFAULT,

    ALTER COLUMN foo_timestamp TYPE timestamp with time zone

    USING

        timestamp with time zone 'epoch' + foo_timestamp * interval '1 second',

    ALTER COLUMN foo_timestamp SET DEFAULT now();

To rename an existing column:

ALTER TABLE distributors RENAME COLUMN address TO city;

To rename an existing table:

ALTER TABLE distributors RENAME TO suppliers;

To add a not-null constraint to a column:

ALTER TABLE distributors ALTER COLUMN street SET NOT NULL;

To remove a not-null constraint from a column:

ALTER TABLE distributors ALTER COLUMN street DROP NOT NULL;

To add a check constraint to a table and all its children:

ALTER TABLE distributors ADD CONSTRAINT zipchk CHECK (char_length(zipcode) = 5);

To remove a check constraint from a table and all its children:

ALTER TABLE distributors DROP CONSTRAINT zipchk;

To remove a check constraint from one table only:

ALTER TABLE ONLY distributors DROP CONSTRAINT zipchk;

(The check constraint remains in place for any child tables.)

To add a foreign key constraint to a table:

ALTER TABLE distributors ADD CONSTRAINT distfk FOREIGN KEY (address) REFERENCES addresses (address) MATCH FULL;

To add a (multicolumn) unique constraint to a table:

ALTER TABLE distributors ADD CONSTRAINT dist_id_zipcode_key UNIQUE (dist_id, zipcode);

To add an automatically named primary key constraint to a table, noting that a table can only ever have one primary key:

ALTER TABLE distributors ADD PRIMARY KEY (dist_id);

To move a table to a different tablespace:

ALTER TABLE distributors SET TABLESPACE fasttablespace;

To move a table to a different schema:

ALTER TABLE myschema.distributors SET SCHEMA yourschema;

To recreate a primary key constraint, without blocking updates while the index is rebuilt:

CREATE UNIQUE INDEX CONCURRENTLY dist_id_temp_idx ON distributors (dist_id);
ALTER TABLE distributors DROP CONSTRAINT distributors_pkey,
   ADD CONSTRAINT distributors_pkey PRIMARY KEY USING INDEX dist_id_temp_idx;