What is the PostgreSQL equivalent to the TSQL "go" statement?

Question

In T-SQL, I can state:

IF EXISTS (SELECT name 
           FROM   sysobjects 
           WHERE  name = 'tableName') 
  DROP TABLE [dbo].[tableName] 
go 

What is the batch terminator equivalent (i.e. "go") for the following SQL command?

DROP TABLE IF EXISTS tableName

Solution 1

The PostgreSQL equivalent would be:

DROP TABLE IF EXISTS tableName;

So the terminator is simply the SQL standard semi-colon ;.

Solution 2

From SQL Server documentation:

GO is not a Transact-SQL statement; it is a command recognized by the sqlcmd and osql utilities and SQL Server Management Studio Code editor.

The syntax permits to have a number, after the keyword go, to repeat previous lines a number of times. Syntax is:

GO [count]

It separates batch. There is not an equivalent for PostgreSQL. The semicolon ends a statement, not a batch. And it is not possible to specify a number of executions.

Go references: https://msdn.microsoft.com/it-it/library/ms188037.aspx

Solution 3

It depends. GO is separator (delimiter) - it is special keyword that is not used in any SQL statement. PostgreSQL uses semicolon ; as separator. In console psql you can use \g

postgres=# select 10 as a
postgres-# \g
+----+
| a  |
+----+
| 10 |
+----+
(1 row)

but it is not used often. Sometimes people uses \gset that execute SQL statement and store result to psql local variables. PostgreSQL can use semicolon, because PostgreSQL SQL statements has not to contain this symbol - It is different against T-SQL, because T-SQL allows some procedural constructs directly in SQL - and then T-SQL requires special separator. PostgreSQL doesn't allow it - procedural code is entered as string - and it is separated by apostrophes or custom string separators. So procedural conditional drop can looks like:

DO $$BEGIN
  IF EXISTS (SELECT * FROM information_schema.tables 
               WHERE table_name = 'someTable') -- attention CASE SENSITIVITY
  THEN
    DROP TABLE "someTable"; -- attention CASE SENSITIVE syntax
  END IF; 
END $$;

or more simply DROP TABLE IF EXISTS someTable (case insensitive syntax). I used custom string separator $$

DO $$ -- DO command with start of string (started by custom separator)
...   -- some procedural code
$$ ;  -- end string by custom separator and semicolon as end of DO command

Comments

[NathanAldenSr]

I disagree that the semicolon is the equivalent of GO. GO is a batch statement terminator. Several statements may be executed within a batch, and GO terminates that batch. GO is important because it can be used to create a single script containing normal statements and statements that must be the only statement in a batch.