Intranet system, the number at the time of submission has to do anti-duplication judgment, but the same number submitted once changed to two times.
Intranet system,
Service-Side Php+mysql
The value of the Data table field is written in PHP to make a judgment, the normal hint of the same number can not be repeated insert data, but sometimes when the operation was clearly submitted only once, but found that the same time and the same second write two.
The warrior knows what's going on.
------Solution--------------------
seconds concurrency problem.
For example, there are two requests, a and a
AB, after judging whether to repeat the position, and then when a is inserted, B will follow the insert.
This can be written to avoid repeated insertions.
For example, the test table has two fields Name,value
INSERT into Test (name, value) of select ' Fdipzone ', ' 123 ' from DUAL WHERE ' Fdipzone ' isn't in (select name from test);
