sql - SQLite Like % and _

Question

I can't figure out what the underscore character does in an SQLite like statement. The wildcard character, %, is probably the same as in most other SQL databases.

So, what does the _ character do?

Answer 1

It is standard SQL that in LIKE expressions:

• % matches any sequence of characters, including an empty one. It is equivalent to .* in a regular expression.
• _ matches a single character. It is equivalent to . in a regular expression.

• You can choose a character for escaping %, _ and itself itself with:

  ... WHERE expr LIKE 'a_b%c\d\%\_' ESCAPE ''
  

  This will match a×b×××cd%_ or a×bcd%_ but not abcd%_ nor a×b×××cd%_.

Additionnally with SQLite you have the GLOB keyword which behaves exactly the same way, except that % becomes * and _ becomes ?.