Dripping pipe to shower

[db60]

my cold water pipe from cold tank to shower has started to drip. On inspection I see it is dripping from the soldered end of the tap connector.
1) Can I apply something to it like Plumbers Mait to stop the leak?
2) Also why does a soldered joint, which is underneath the bath, suddenely start to drip after many years?

[Doc Spock]

Have to be replaced I am afraid. Nothing of a job, if you don't fancy using blowtorch use compression joints.

The integrity of a soldered joint can sometimes fail due to age, stress etc. It may not have been done too competently originally.

[Hawkwalk]

Plumbers mate will not stop the leak. You need a new joint putting on. It wont cost much for a plumber to come and do this.