8.10. Oracle Compatible Queries

8.10.1. Pseudocolumns
8.10.2. Queries

8.10.1. Pseudocolumns

This chapter introduces Oracle pseudocolumns that LightDB has supported.

  • ORA_ROWSCN

8.10.1.1. ORA_ROWSCN

In LightDB, ORA_ROWSCN is equivalent to xmin except the type of ORA_ROWSCN is bigint.

Example

    create table foo(a int);
    insert into foo values (1);
    select ora_rowscn, xmin from foo;
   

8.10.2. Queries

The following queries are supported:

  • DUAL Table

DUAL table is a virtual table provided by the system. Use when executing SQL where access to a base table is not required, such as when performing tests to get result expressions such as functions and operators.

Example

In the following example, the current system date is returned.

   SELECT  CURRENT_DATE  "date" FROM DUAL;
       date
   ------------
    2013-05-14
   (1 row)