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Dynamic column name while operating with NEW/OLD
Posted by: Alexander Panyutin
Date: February 04, 2015 07:52AM

Hi, all.

I've trying to make next:
1. I have 5 ( or more ) tables, changes in which I need to monitor externally.
2. So I've trying to create triggers model like that:
CREATE TRIGGER `thisTriggerName` AFTER INSERT ON `myTableName`
FOR EACH ROW BEGIN
	SET @table_name := 'myTableName';
	SET @current_version := '';
	SET @columns := '';

	SELECT `version`, `columns` INTO @current_version, @columns FROM `lookup_tables_versions` WHERE `table` = @table_name;
	
	SET @current_version := @current_version + 1;

	SET @data :='';
	SET @pos := 0;
	SET @operative_columns := CONCAT_WS('', @columns);
	split:	WHILE ( LENGTH( @operative_columns ) > 0 ) DO
		SET @pos := LOCATE( ',', @operative_columns );

		IF ( @pos = 0 ) THEN SET @pos := LENGTH( @operative_columns ) + 1;
		END IF;

		SET @field := SUBSTRING( @operative_columns, 1, @pos - 1 );
		SET @operative_columns := SUBSTRING( @operative_columns, @pos + 1 );
		SET @data := CONCAT_WS( '', @result, '<', @field, '>', NEW.@field, '</', @field, '>' );
	END WHILE split;

	INSERT INTO `lookup_tables_logs` SET `table`=@table_name, `event`='insert', `pk`=NEW.id, `version`=@current_version, `data`=@data
	REPLACE INTO `lookup_tables_versions` SET `table`=@table_name, `version`=@current_version, `columns`=@columns;
END;

1. Is there any way to get NEW.@field ( @field is a variable, which value means one of columns set )
2. Maybe exists some serialization function ? ( I mean `data` = SERIALIZE( NEW ) )
3. Is there any way to proceed with binlog in SQL-like syntax ?

Thank you for your time.

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Dynamic column name while operating with NEW/OLD
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