The Error Log user_defined_field : sequence of characters in [a-zA-Z0-9_] class comparator : {== | != | <> | >= | => | <= | =< | < | >} value : { string_literal |  integer_literal |  float_literal |  error_symbol |  priority } count :  integer_literal window_size :  integer_literal string_literal : sequence of characters quoted as ’...’ or "..." integer_literal : sequence of characters in [0-9] class float_literal : integer_literal [. integer_literal ] error_symbol : valid MySQL error symbol such as ER_ACCESS_DENIED_ERROR or ER_STARTUP priority : { ERROR | WARNING | INFORMATION } Simple conditions compare a field to a value or test field existence. To construct more complex conditions, use the  AND  and  OR  operators. Both operators have the same precedence and evaluate left to right. To escape a character within a string, precede it by a backslash ( \ ). A backslash is required to include backslash itself or the string-quoting character, optional for other characters. For convenience,  log_filter_dragnet  supports symbolic names for comparisons to certain fields. For readability and portability, symbolic values are preferable (where applicable) to numeric values. Error symbols are recognized only in comparisons with the  err_code  field and user-defined fields. To find the error symbol corresponding to a given error code number, use one of these methods: •Check the list of server errors at Server Error Message Reference. •Use the  perror  command. Given an error number argument,  perror  displays information about the error, including its symbol. •Error codes can be specified in numeric form or as the corresponding error symbol. For example, ER_STARTUP  is the symbolic name for error  1408 , so these comparisons are equivalent: •Event priority values 1, 2, and 3 can be specified as  ERROR ,  WARNING , and  INFORMATION . Priority symbols are recognized only in comparisons with the  prio  field. These comparisons are equivalent: IF prio == INFORMATION THEN ... IF prio == 3 THEN ... IF err_code == ER_STARTUP THEN ... IF err_code == 1408 THEN ... 1037