MySQL Search w/ Ordered Wildcards, and Extracting Their Values

问题

Is it possible to do a wildcard search, and extract the values of the wildcards and put them into a MySQL result? Preferably, I'd also like to label the wildcards. Continue reading to see what I mean.

EXAMPLE: Consider a database table with the following structure.

+----+-------------------+
| id | content           |
+========================+
| 1  |  %1.%2.%3         |
+----+-------------------+
| 2  |  Hey %name.       |
+----+-------------------+

First, note that this is just an example. I am not storing multiple values in a single database field. See here: Is storing a delimited list in a database column really that bad?

Instead, I want to know if it is possible to have wildcards in a database, and then compare that with user input. In other words, I would like to take user input, such as 2.bla.^7 or similar, and then return that respective row--%.%.%. I would then like to take those wildcards, and return them as part of the MySQL result. Below is an example PHP mysql_fetch_assoc() result based on what I'm looking for. The result obviously doesn't need to be laid out exactly like this, but this is the sort of result that I'm looking for.

EXAMPLE:

/************************
 * Input:    2.bla.^7   *
 ************************/
Array
(
    [0] => Array
    (
        [id] => 1,
        [content] => %1.%2.%3
    ),

    [1] => Array
    (
        [1] => 2,
        [2] => bla,
        [3] => ^7
    )
)

/************************
 * Input:   Hey Matt.   *
 ************************/
Array
(
    [0] => Array
    (
        [id] => 2,
        [content] => Hey %1.
    ),

    [1] => Array
    (
        [name] => Matt
    )
)

I understand that what I'm looking for is likely fairly complicated, or specialized for my unique case. If you can point me in the right direction, I would hugely appreciate it! I don't even know if this is possible--if it's not, an alternative solution would be greatly appreciated! However, I want the database structure to stay as close to the same as possible.

Thank you so much!

回答1:

Indeed there is no ready-to-go solution. Here is what I would do:

1) Add 3 special columns like_pattern, regexp_pattern and placeholders. Their values are calculated from the column content either in PHP before loading data into the table, or in BEFORE INSERT/UPDATE TRIGGERs.

like_pattern VARCHAR(N) - LIKE pattern for reverse search
regexp_pattern VARCHAR(N) - Regexp pattern for extracting parts later in PHP
placeholders VARCHAR(N) - Comma-separated list of placeholder names

Here is the example:

+----+-------------+--------------+--------------------+--------------+
| id | content     | like_pattern | regexp_pattern     | placeholders |
+====+=============+==============+====================+==============+
| 1  |  %1.%2.%3   | %.%.%        | ^(.*)\.(.*)\.(.*)$ | 1,2,3        |
+----+-------------+--------------+-+------------------+--------------+
| 2  |  Hey %name. | Hey %.       | ^Hey (.*)\.$       | name         |
+----+-------------+--------------+--------------------+--------------+

2) For a given string search record using like_pattern:

SELECT * FROM patterns WHERE 'Hey Nathanael.' LIKE like_pattern;

Be aware that simple index can not speed up this query because we perform a reverse search, so depending on how big your table is you probably will need a different solution.

3) Match the string 'Hey Nathanael.' against returned regexp_pattern using PHP's preg_match() or ereg(). You will get placeholder values.

4) Combine them with placeholder names from the column placeholders.

That's it.

回答2:

Don't you just want to do:

SELECT * FROM patterns WHERE 'user input' LIKE content;

See it on sqlfiddle.

来源：https://stackoverflow.com/questions/10693667/mysql-search-w-ordered-wildcards-and-extracting-their-values

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regex

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wildcard