Modules/MTA-MySQL/mysql unbuffered query: Difference between revisions
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<pageclass class="#AA7592" subcaption="MTA-MySQL Module"></pageclass> | |||
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{{ModuleFunction|MTA-MySQL}} | {{ModuleFunction|MTA-MySQL}} |
Latest revision as of 17:59, 5 January 2011
This function is provided by the external module MTA-MySQL. You must install this module to use this function. | |
Executes an unbuffered 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.
IMPORTANT: Unbuffered queries are to iterate a set of results improving the performance since they are not pre-loaded in memory, so if you execute an unbuffered query you must iterate all the result rows. For more information about unbuffered queries visit http://dev.mysql.com/doc/refman/5.0/en/mysql-use-result.html
Syntax
MySQLResult mysql_unbuffered_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_unbuffered_query(handler, "SELECT * FROM some_table") if (not result) then outputDebugString("Error executing the query: (" .. mysql_errno(handler) .. ") " .. mysql_error(handler)) else local numrows = 0 for result,row in mysql_rows(result) do -- We MUST iterate all the query resulting rows numrows = numrows + 1 end outputDebugString("The query returned a total of " .. numrows .. " rows") mysql_free_result(result) -- Freeing the result is IMPORTANT end
See also
Result managing functions
- mysql_data_seek
- mysql_fetch_field
- mysql_fields
- mysql_fetch_lengths
- mysql_fetch_row
- mysql_rows
- mysql_fetch_assoc
- mysql_rows_assoc
- mysql_field_length
- mysql_field_name
- mysql_field_seek
- mysql_field_tell
- mysql_num_fields
- mysql_num_rows
- mysql_result
- mysql_free_result
- mysql_null
MySQL handler functions
- mysql_connect
- mysql_close
- mysql_errno
- mysql_error
- mysql_ping
- mysql_select_db
- mysql_escape_string
- mysql_affected_rows
- mysql_change_user
- mysql_get_character_set_info
- mysql_get_client_info
- mysql_get_client_version
- mysql_get_host_info
- mysql_get_proto_info
- mysql_get_server_info
- mysql_get_server_version
- mysql_hex_string
- mysql_info
- mysql_insert_id
- mysql_query
- mysql_unbuffered_query
- mysql_set_character_set
- mysql_stat
- mysql_warning_count