Why is MySQL matching strings and integers in a way I don't expect? -

i have mysql database following column:

    +-----+     | vpn |     +-----+     | 11a |

when use query:

select vpn vpn_map  vpn=11;

it returns:

    +-----+     | vpn |     +-----+     | 11a |

but if query:

select vpn vpn_map vpn=lla;

i get:

error 1054 (42s22): unknown column '11a' in 'where clause'

why doesn't previous query match? match if do:

select vpn vpn_map vpn='lla';

but vpn='11' won't match anything. missing here?

11a not integer , have use " around them otherwise error.

select vpn vpn_map vpn="lla";

Single