The result of git merge is git merge Already up-to-date. How to solve it?

Question

I pull updates from the remote warehouse. If I use git pull, I will get normal results

$ git pull local gaoyx_work
From localhost:~/publicOpinion
 * branch            gaoyx_work -> FETCH_HEAD
Merge made by recursive.
 workDir/dbConnector.php |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

But using git fetch and git merge will not succeed

$ git fetch local gaoyx_work
From localhost:~/publicOpinion
 * branch            gaoyx_work -> FETCH_HEAD
$ git merge local/gaoyx_work
Already up-to-date.

I don’t know much about git merge, I don’t know what’s going on, and I don’t know how to solve it