SQL - Release Table

GSAK (Geocaching Swiss Army Knife)

SQL - Release Table

Warning: The SQL command was the first introduction of SQL to the macro language. It has many limitations and quirks and is now deprecated. It is provided for here for backwards compatibility only. It is very much recommended that you use the more complete and robust SQLite database engine. See the SQLite() function.

Allows you to release any open [1] table from memory, including temporary tables created with ASSIGN TO. This is a non-standard SQL statement.

Syntax:

RELEASE TABLE tablename

Example:

# Release table caches from memory in case updated outside the SQL engine
$status = sql("Release Table Caches","")

# Now query and open the caches table
$status = sql("Select * from caches","")

[1] The SQL engine is memory based. The term "open" here really just means that it is available in memory. You could reference a table using any of the SQL commands (SELECT is the most common). When you reference a table in any way (open it) for the first time, a copy of the table data is stored in memory. All further actions on that table are done from this memory table until you issue a RELEASE command. If you want to make sure any changes to the "memory" table are saved you must use COMMIT before you RELEASE the table

Note: You can use the RELEASE and COMMIT commands to simulate "transactions". So you could do a whole bunch of update SQLs, but only COMMIT the updates to disk at the end of the "good" transaction. If there was an error condition detected in your macro, you could issue a RELEASE command which would effectively "Roll Back" all your updates. See Commit for an example.