"a"+'b'+"c",mysql中两个双引号和一个单引号组合是什么意思

Question

For example
SELECT "hello"'jacky'"hi" as value from dual;
the result is hellojackyhi
But it confuse me that the use of this pattern "a"+'b'+"c" .
What does this pattern exactly mean?It's a use of double quotes and single quote, is it mean I can always combine 3 string using this pattern "a"+'b'+"c" ?

Answer 1

MySQL has a "feature" where it concatenates strings that are adjacent (and separated by a space):

select 'a' 'b' 'c'
---> abc

This works for both single quotes and double quotes. Of course, double quotes might also be a column name.

So, this is a short-cut for string concatenation. I strongly recommend that you use CONCAT() instead, so the intention is clear.