Question

Can’t seem to find documentation on a particular formation of SQL using the LIKE operator. Using MySQL, a typical query for multiple words using the LIKE operator may look like this:

SELECT * from table AS t WHERE t.col LIKE '%word1%' AND t.col LIKE '%word2%'

Although the following statement also works, the rows returned will vary depending on the order of the words in the query. For example:

SELECT * from table WHERE col LIKE '%word1%' '%word2%'

executes without the AND boolean, but with different results from:

SELECT * from table WHERE col LIKE '%word2%' '%word1%'

My question is, what is actually happening when using this formation of the query instead of using boolean?

Answer 1

From the manual:

Quoted strings placed next to each other are concatenated to a single
string. The following lines are equivalent:

'a string'

'a' ' ' 'string'

So, what’s happening is that '%word1%' '%word2%' is being interpreted as ‘%word1%%word2%’