Modules/MTA-MySQL/mysql query: Difference between revisions

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(New page: __NOTOC__ Executes a query in the server and retreives the result. '''Important:''' It is '''strongly''' recommended to call mysql_free_result aft...)
 
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  '''Important:''' It is '''strongly''' recommended to call [[Modules/MTA-MySQL/mysql_free_result|mysql_free_result]] after a query,
  '''Important:''' It is '''strongly''' recommended to call [[Modules/MTA-MySQL/mysql_free_result|mysql_free_result]] after a query,
  specially if it returns some data. Query results can be automatically deleted by the lua garbage collector, so if you '''forget'''
  specially if it returns some data. Query results can be automatically deleted
to free a result it will be freed at some time in the future, but it doesn't know the real result data size in memory so it can
by the lua garbage collector, so if you '''forget''' to free a result it will be
delay the memory destroying more than it should.
freed at some time in the future, but it doesn't know the real result data size
in memory so it can delay the memory destroying more than it should.


==Syntax==
==Syntax==

Revision as of 18:11, 13 January 2008

Executes a query in the server and retreives the result. 

Important: It is strongly recommended to call mysql_free_result after a query,
specially if it returns some data. Query results can be automatically deleted
by the lua garbage collector, so if you forget to free a result it will be
freed at some time in the future, but it doesn't know the real result data size
in memory so it can delay the memory destroying more than it should.

Syntax

MySQLResult mysql_query ( MySQLConnection handler, string query )

Required arguments

  • handler: A valid MySQL link
  • query: The executing query

Returns

In case of error this function returns nil. IF not, a MySQLResult handler. Check the MySQL result managing functions to see how to retreive the data from it.

Example

Example 1: 

local result = mysql_query(handler, "SELECT * FROM some_table")
if (not result) then
  outputDebugString("Error executing the query: (" .. mysql_errno(handler) .. ") " .. mysql_error(handler))
else
  mysql_free_result(result) -- Freeing the result is IMPORTANT
end

See also

Result managing functions

MySQL handler functions

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