SELECT from nothing?

Solution 1:

It's not consistent across vendors - Oracle, MySQL, and DB2 support dual:

SELECT 'Hello world'
  FROM DUAL

...while SQL Server, PostgreSQL, and SQLite don't require the FROM DUAL:

SELECT 'Hello world'

MySQL does support both ways.

Solution 2:

In Oracle:

SELECT 'Hello world' FROM dual

Dual equivalent in SQL Server:

SELECT 'Hello world' 

Solution 3:

Try this.

Single:

SELECT *  FROM (VALUES ('Hello world')) t1 (col1) WHERE 1 = 1

Multi:

SELECT *  FROM (VALUES ('Hello world'),('Hello world'),('Hello world')) t1 (col1) WHERE 1 = 1

more detail here : http://modern-sql.com/use-case/select-without-from

Solution 4:

Here is the most complete list of database support of dual from https://blog.jooq.org/tag/dual-table/:

In many other RDBMS, there is no need for dummy tables, as you can issue statements like these:

SELECT 1;
SELECT 1 + 1;
SELECT SQRT(2);

These are the RDBMS, where the above is generally possible:

• H2
• MySQL
• Ingres
• Postgres
• SQLite
• SQL Server
• Sybase ASE

In other RDBMS, dummy tables are required, like in Oracle. Hence, you’ll need to write things like these:

SELECT 1       FROM DUAL;
SELECT 1 + 1   FROM DUAL;
SELECT SQRT(2) FROM DUAL;

These are the RDBMS and their respective dummy tables:

• DB2: SYSIBM.DUAL
• Derby: SYSIBM.SYSDUMMY1
• H2: Optionally supports DUAL
• HSQLDB: INFORMATION_SCHEMA.SYSTEM_USERS
• MySQL: Optionally supports DUAL
• Oracle: DUAL
• Sybase SQL Anywhere: SYS.DUMMY

Ingres has no DUAL, but would actually need it as in Ingres you cannot have a WHERE, GROUP BY or HAVING clause without a FROM clause.