Question

How can I select all table names in PostgreSQL?

Answer and Explanation

To select all table names in PostgreSQL, you can query the pg_tables system catalog. This catalog contains information about all tables in your database. Here’s how you can do it:

1. Using a Simple Query:

The most common way to list table names is to use a SELECT statement on the pg_tables system catalog. You’ll typically want to filter out system tables, which are located in schemas like pg_catalog.

2. Example SQL Query:

SELECT tablename
FROM pg_tables
WHERE schemaname='public';

- This SQL query retrieves all table names (tablename) from the pg_tables catalog where the schema name is 'public'. The 'public' schema is where user-created tables are commonly stored. If you're using a different schema, you'll need to adjust the WHERE clause.

3. Retrieving tables from all Schemas:

If you want to list all user tables from all schemas (not only 'public'), you can use this query:

SELECT tablename,
schemaname
FROM pg_tables
WHERE schemaname NOT IN ('pg_catalog', 'information_schema');

This query excludes tables in system schemas like pg_catalog and information_schema, which are not user tables.

4. Explanation:

- pg_tables is a system catalog that stores information about tables in a PostgreSQL database.

- tablename is a column in pg_tables that holds the name of each table.

- schemaname is the schema the table belongs to, and filtering by 'public' or excluding system schemas like 'pg_catalog' helps to isolate tables you've created.

5. Accessing Results:

- You can execute this SQL query using any PostgreSQL client, such as psql, pgAdmin, or any other database tool.

6. Alternative methods:

- While using the pg_tables catalog is most common, there are other ways like querying the information_schema. But, pg_tables is a simple, direct method suitable for most use cases.

By using these SQL queries, you can easily select all table names in your PostgreSQL database and from any specific schema.

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