第一句是SQL循环用的，这个条件下，会读取所有的记录，因为会一直循环;

第二句是游标里的，@@fetch_status=0   等于0时，说明游标是成功的.

(The first sentence is for SQL loop. Under this condition, all records will be read, because it will loop all the time;
The second sentence is in the cursor, @ @ fetch_ When status = 0 equals 0, the cursor is successful
)

第一句是SQL循环用的，这个条件下，会读取所有的记录，因为会一直循环;

第二句是游标里的，@@fetch_status=0   等于0时，说明游标是成功的.

(The first sentence is for SQL loop. Under this condition, all records will be read, because it will loop all the time;
The second sentence is in the cursor, @ @ fetch_ When status = 0 equals 0, the cursor is successful
)