Two application program design,
A son do a master end end,
When master end to insert information database, change a value, control end has reminded the words or dialog
I want to ask this statement what to write, how to achieve uninterrupted access to judge the database data update

For example: the main application to modify the (' position ', '5') and (' working hours') on the value of the '23'
Son and end receives commands to modify the pop-up dialog FORM2
May be a bit fuzzy looking than burke said

How can such a judgment? How to achieve a certain time of the database access update (cycle is 30 s or less)?

CodePudding user response:

By the way, could you tell me how to modify the DBGrid display column!
For example: working hours in two lines show
Work
Time
Or directly to vertical display

As the

between

CodePudding user response:

It is recommended to use DataSnap callback mechanism,

CodePudding user response:

XE version support after the callback mechanism,

CodePudding user response:

Wait a day also didn't anyone tell me?

CodePudding user response:

Update I have solved this problem, is a database of judgment should be how to operate?

CodePudding user response:

Timing query is obviously not a good way,
As the second floor, three layer structure by rewriting the client to a mass of data message informing other client

CodePudding user response:

Server callback more timely, less resource consumption

CodePudding user response:

reference lyhoo163 reply: 3/f

XE version support after the callback mechanism,

I am using Delphi7 have?
Specific what to do?

CodePudding user response:

refer to 6th floor FlashDance response:

time query is obviously not a good way,
As the second floor, three layer structure by rewriting the client to a mass of data message is good for you to notice other client

Specific use step is what?

CodePudding user response:

references 9 f dp15262112 response:

Quote: refer to the sixth floor FlashDance response:

Timing query is obviously not a good way,
As the second floor, three layer structure by rewriting the client to a mass of data message is good for you to notice other client

Specific use step is what?

DataSnap what are a few words can finish speak, introductory tutorial a handful, first introduction to write your own code, to ask for help to modify

CodePudding user response:

D7 no callback, XE version to support the callback mechanism,

CodePudding user response:

1. The end time to query the database server, this way to the database server pressure a bit big, and you need to be in the main application to update, also update the tags for the record, said the record has been modified, the son side read tag, naturally know recorded changed,

2. Make a similar to TCP communications server on the database server, when you update the database main end, send a message to a communication server at the same time, in this way, you can connect your own revision content can be through the socket message sent to you together login to the socket server each endpoint, son end even don't have to read the database, you will know...