How to check if db exists in PostgreSQL?
To view all of the defined databases on the server you can use the \list meta-command or its shortcut \l .In PostgreSQL, the EXISTS operator is used to test for the existence of rows in a subquery.It is generally used with correlated subqueries. If the subquery returns at least one row, the result of EXISTS is true. In case the subquery returns no row, the result is of EXISTS is false.In PostgreSQL, the “information_schema”, “pg_catalog”, and “pg_tables” are used to check the existence of a specific table in the current database. All these methods retrieve a boolean true or false, which indicates the presence of the selected table in the current database.

How to access database in PostgreSQL : Connect and Access PostgreSQL Database Server using psql:

  1. Step 1: Launch SQL Shell (psql) program tool.
  2. Step 2: To use the default value specified in the square bracket [ ], just press Enter and move on to the next line.
  3. Step 3: Now, interact with the database server using SQL commands.

How to check database and table in PostgreSQL

PostgreSQL List All Tables

  1. Step #1: Log in to the SQL SHELL.
  2. Step #2: Check Available Databases.
  3. Step #3: Establish a Connection With the Desired Database.
  4. Step #4: List All Tables.
  5. Step #5: List All Tables With Detailed Information.
  6. Step #1: Open pgAdmin.
  7. Step #2: Open Query Tool.
  8. Step #3: List Tables Using pg_catalog.

What is the command to check current database in PostgreSQL : The function current_database() returns the name of the current database: SELECT current_database(); It's an SQL function, so you must call it as part of an SQL statement.

By using the EXISTS condition with the SELECT statement, you can perform more complex queries and retrieve data based on the existence of records in related tables. Remember to adapt the table and column names according to your own database schema when applying EXISTS with the SELECT statement.

To define if the database in question exists in SQL Server, we can use the standard T-SQL means, querying the DB_ID() function or the sys. databases catalog view. Which one to choose depends on your preferences.

How do you check if a table already exists

Use the EXISTS clause in conjunction with a SELECT statement to check for a table's existence. Replace your_table_name with the name of your table and your_database_name with the name of your database.Connect to PostgreSQL from the command line. At the command line in your operating system, type the following command. user@user-pc:~$ sudo -i -u postgres postgres@user-pc:~$ psql psql (9.3. 5, server 9.3.pgAdmin

  • Open pgAdmin and enter your password to connect to the database server.
  • Expand the Servers section in the menu on the left side of the screen.
  • Expand the Databases section. The tree now shows a list of all databases on the server. Click the Properties tab to see more information about each database.


Type “\c” followed by a database name to select a database using psql. Type “psql hostname port number username databasename” to select a database using cmd. Open pgAdmin > select desired database> and open the “Query Tool” to select a database using pgAdmin.

How to see databases and users in PostgreSQL : Postgres provides different built-in commands to find the list of users, databases, schemas, or tables. For instance, the “\du”, “\l”, “\dn”, and “\dt” commands are used to find the list of users, databases, schemas, and tables, respectively.

How do I find the current database in SQL : You can use the 'dbname' option to retrieve the name of the current database.

How do you know this is a database

A database is an organized collection of structured information, or data, typically stored electronically in a computer system. A database is usually controlled by a database management system (DBMS).

Use EXISTS to identify the existence of a relationship without regard for the quantity. For example, EXISTS returns true if the subquery returns any rows, and [NOT] EXISTS returns true if the subquery returns no rows. The EXISTS condition is considered to be met if the subquery returns at least one row.1. SELECT query with WHERE clause: This query can be used to check if a specific value already exists in a column of the table. For example, "SELECT * FROM table_name WHERE column_name = 'value'". If the query returns any results, it means that the value already exists in the table.

How to show databases in command line : Run the following query to show list of databases: SHOW DATABASES; You can run this statement from MySQL Command Line Client, MySQL Shell, as well as from any GUI tool that supports SQL—for example, dbForge Studio for MySQL. MySQL returns the results in a table with one column—Database.