问题
I am currently searching my database with a query (using JDBC) like this:
"... AND LCASE(Items.Name) LIKE '%" + searchString.toLowerCase() + "%';"
Now, this is obviously very bad, because it allows for SQL injection as well as insertion of wildcard symbols such as % and _.
My question is, how can I do a query such that even if the searchString contains any of these characters, they will be treated literally?
回答1:
First, don't use LCASE with LIKE unless you're using a case-sensitive locale (which is not the default with MySQL).
As far as escaping those characters, just prefix them with a \ character, so foo%bar becomes foo\%bar.
(It's been a while since I've used Java, but might this work:)
searchString.replaceAll('%', '\\\\%').replaceAll('_', '\\\\_')
(or using a regex):
Regex r = new Regex('(?:%|_)', '\\\\$&');
r.replaceAll(searchString)
As far as preventing SQL injection, just bind the variable as normal:
WHERE LCASE(Items.Name) LIKE ?
And create the bound string like:
'%' + searchString.replaceAll('%', '\\\\%').replaceAll('_', '\\\\_') + '%'
回答2:
According to this, you can escape them using a slash (\) or by specifying your own escape character:
"... AND LCASE(Items.Name) LIKE '%" + searchString.toLowerCase() + "%' ESCAPE '/';"
You'll have to do a search and replace on the mysql LIKE wildcard symbols in your language (Java?), % and _ to replace them with \% and \_ respectively. The other pattern matches you mention above are not (according to the linked docs) supported.
来源：https://stackoverflow.com/questions/4588424/searching-using-mysql-how-to-escape-wildcards