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Pattern Conditions

Overview

The patternConditions module provides functions for processing and generating SQL-like pattern conditions. These conditions allow for pattern matching within SQL queries, including support for logical operators like $or and $and.

Interface

patternType

Defines the structure of pattern conditions, including both positive ($pattern) and negative ($not_pattern) patterns.

• $pattern: Specifies the positive pattern conditions.
• $not_pattern: Specifies the negative pattern conditions.

Functions

processPatternConditions

Processes pattern conditions recursively and generates a string representation.

• Parameters:
  • conditions: The pattern condition object.
  • operatorKeyword: The keyword to be used before the condition (e.g., NOT).
  • subOperator: The sub-operator to be used between multiple conditions (e.g., AND, OR).
• Returns: The generated pattern conditions as a string.

patternConditions

Generates SQL-like pattern conditions based on the provided input.

• Parameters:
  • condition: The patternType object containing conditions.
  • subOperator (optional): The sub-operator to be used between multiple conditions.
• Returns: The generated pattern conditions as a string.

Usage

Example usage of the patternConditions module:

import { patternConditions } from "mysql-query-geniex";;

const condition = {
    "$pattern": {
        field1: 'value1%',
        "$or": {
            field2: '%value2',
            field3: '%value3%'
        }
    },
    "$not_pattern": {
        field4: '%value4',
        "$and": {
            field5: '_value%',
            field6: 'val%ue'
        }
    }
};

const sqlPatternConditions = patternConditions(condition);
console.log(sqlPatternConditions);

This will output the SQL-like pattern conditions string based on the provided conditions.

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The wildcard characters and provide more examples:

A wildcard character is used to substitute one or more characters in a string.

Wildcard Character	Description	Example	Matches
%	Matches zero or more characters, including none.	'%apple%'	'apple', 'pineapple', 'caramel-apple', etc.
_	Matches exactly one character.	'_at'	'cat', 'bat', 'hat', but not 'at'
[charlist]	Matches any single character within the set.	'[bc]at'	'bat', 'cat'
[^ charlist]	Matches any single character not within the set.	'[^abc]at'	'mat', 'hat', 'sat', but not 'cat'
\	Escapes special characters to be treated as literals.	'10%'	'10%' in the data
?	Matches any single character (Equivalent to _).	'c?t'	'cat', 'cot', but not 'cart'
*	Matches zero or more occurrences of any character.	'c*t'	'cat', 'ct', 'cart', 'cot', 'ceiling'
+	Matches one or more occurrences of any character.	'c+t'	'cat', 'ct', but not 'cot', 'ceiling'
a	Matches any alphabetic character.	'%acat'	'acat', 'bcat', 'ccat', but not '9cat'
d	Matches any digit.	'%d%'	'1', '2', '3', etc.
s	Matches any whitespace character.	'%s%'	' ', ' ', etc.
w	Matches any word character (alphanumeric and underscore).	'w+'	'word', '123', 'word123', but not '!'
Z	Matches the end of the string.	'wordZ'	'word' at the end of the string
{ n }	Matches exactly 'n' occurrences of the previous character.	'ba{2}'	'baa', but not 'ba'
{ n, m }	Matches at least 'n' and at most 'm' occurrences.	'ba{1,3}'	'ba', 'baa', 'baaa', but not 'baaaa'
^	Matches the start of the string.	'^apple'	'apple' at the beginning of the string
$	Matches the end of the string.	'apple$'	'apple' at the end of the string
	Matches a word boundary (position between a word character and a non-word character).	'word'	'word' as a separate word, not within another word
B	Matches a non-word boundary (opposite of ).	'BwordB'	'word' within another word, not as a separate word
d{ 3 }	Matches exactly three digits.	'd{3}'	'123', '456', etc.
w{ 4 }	Matches exactly four word characters.	'w{4}'	'word', '1234', but not '!@#%'
[a - z]	Matches any lowercase alphabetic character.	'[a-z]%'	Words starting with a lowercase letter
[A - Z]	Matches any uppercase alphabetic character.	'[A-Z]%'	Words starting with an uppercase letter

MORE:

Here are some more wildcard characters and their descriptions:

Wildcard Character	Description	Example	Matches
[0 - 9]	Matches any digit from 0 to 9.	'[0-9]%'	Words starting with a digit
[a - zA - Z]	Matches any alphabetic character (lowercase or uppercase).	'[a-zA-Z]%'	Words starting with any letter
[^ 0 - 9]	Matches any character except digits.	'^[^0-9]'	Words that don't start with a digit
.	Matches any single character except newline.	'a.'	'ab', 'ac', but not 'a' or 'abc'
*	Matches zero or more occurrences of the previous character.	'ab*'	'a', 'ab', 'abb', 'abbb', etc.
+	Matches one or more occurrences of the previous character.	'ab+'	'ab', 'abb', 'abbb', but not 'a'
?	Matches zero or one occurrence of the previous character.	'ab?'	'a', 'ab', but not 'abb' or 'abc'
(... )	Groups multiple tokens together.	'(abc)+'	'abc', 'abcabc', but not 'ab' or 'abcd'

These wildcard characters, when used in combination with regular expressions or pattern matching functions in SQL queries, provide powerful tools for searching and filtering data in databases.

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