ld cannot find -lmysqlclient

Hello ! I compiled PHP with the mysql external support but I had a "mysql ran out of memory" error perfoming a big query. As I didn't find a way to extend the mysql client cache (if you have a solution don't hesitate...) I decided to compile PHP again this time with the mysql built-in support. You can imagine how surprised I was when "make" exited with an error telling : ld cannot find -lmysqlclient. If ld is searching for mysqlclient.a It won't find It because It doesn't exist. The are only libmysqlclient* files. Note that I installed mysql correctly ! What's the problem ? Thank you. Patrice