在MYSQL select语句中将'％'与列名一起使用？

Question

I have a query that looks at partial matches within two mysql tables to make a join:

SELECT table1.column, table2.column FROM table1, table2 WHERE table1.val LIKE table2.val

This works fine as a join, but... some of the values in table2 are actually substrings of the values in table one—specifically they're urls. So, table1.val might equal http://google.com while table2.val = google.com.

How do I use the '%' operator around the table2 val to make this comparison.

Thanks in advance!

Answer 1

Like this:

... WHERE table1.val LIKE CONCAT('%', table2.val, '%')

Note that this will not perform as well as table1.val = table2.val , as it must now search all rows in table2 .

Answer 2

Q: How do I use the '%' operator around the table2 val to make this comparison.

A: You don't :)

You can specify a column by name (eg "mycolumn"), by fully qualified name (eg "mytable.myname") or by ordinal (eg "1").