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Displaying posts with tag: dual (reset)
SQL Trouble with dummy tables

As I’m mostly using Oracle for work projects, the concept of the DUAL dummy table has become quite intuitive. I hardly ever think about the days when I was playing around with that table to find out its purpose (e.g. writing into it when DUAL was still a physical object, and thus killing the whole database…)

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) …
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MySQL University: Dual Master Setups With MMM

This Thursday (October 22nd, 13:00 UTC), Walter Heck will present Dual Master Setups With MMM. MMM (Multi-Master Replication Manager for MySQL) is a set of flexible scripts to perform monitoring/failover and management of MySQL master-master replication configurations (with only one node writable at any time). The toolset also has the ability to read balance standard master/slave configurations with any number of slaves, so you can use it to move virtual IP addresses around a group of servers depending on whether they are behind in replication. For more information, see http://mysql-mmm.org/.

For MySQL University sessions, point your browser …

[Read more]
MySQL University: Dual Master Setups With MMM

This Thursday (October 22nd, 13:00 UTC), Walter Heck will present Dual Master Setups With MMM. MMM (Multi-Master Replication Manager for MySQL) is a set of flexible scripts to perform monitoring/failover and management of MySQL master-master replication configurations (with only one node writable at any time). The toolset also has the ability to read balance standard master/slave configurations with any number of slaves, so you can use it to move virtual IP addresses around a group of servers depending on whether they are behind in replication. For more information, see http://mysql-mmm.org/.

For MySQL University sessions, point your browser …

[Read more]
MySQL University: Dual Master Setups With MMM

This Thursday (October 22nd, 13:00 UTC), Walter Heck will present Dual Master Setups With MMM. MMM (Multi-Master Replication Manager for MySQL) is a set of flexible scripts to perform monitoring/failover and management of MySQL master-master replication configurations (with only one node writable at any time). The toolset also has the ability to read balance standard master/slave configurations with any number of slaves, so you can use it to move virtual IP addresses around a group of servers depending on whether they are behind in replication. For more information, see http://mysql-mmm.org/.

For MySQL University sessions, point your browser …

[Read more]
Showing entries 1 to 4