DO

Description

DO executes anonymous code blocks.

A code block is regarded as a function body without parameters. The return value type is void. It is parsed and executed a single time.

Precautions

• Before using a procedural language, you must install it in the current database by running the CREATE LANGUAGE command. PL/pgSQL is installed by default. To install another language, you must specify it.
• To use an untrusted language, you must have the USAGE permission on the programming language or the system administrator permission.

Syntax

DO [ LANGUAGE lang_name ] code;

Parameters

• lang_name

  Specifies the name of the procedural language the code is written in. If omitted, the default language is PL/pgSQL.

• code

  Specifies the programming language code that can be executed. The value must be a character string.

Examples

-- Create the webuser user.
gaussdb=# CREATE USER webuser PASSWORD '********';

-- Grant all permissions on all views in the tpcds schema to the webuser user.
gaussdb=# DO $$DECLARE r record;
BEGIN
    FOR r IN SELECT c.relname table_name,n.nspname table_schema FROM pg_class c,pg_namespace n 
             WHERE c.relnamespace = n.oid AND n.nspname = 'tpcds' AND relkind IN ('r','v')
    LOOP
        EXECUTE 'GRANT ALL ON ' || quote_ident(r.table_schema) || '.' || quote_ident(r.table_name) || ' TO webuser';
    END LOOP;
END$$;

-- Delete the webuser user.
gaussdb=# DROP USER webuser CASCADE;