Two options off the top of my head are:
1) convert your application to web based so that all sites access it via the internet. There is then no need to synchronize data since every uses the same source.
2) Each site runs SQL Server and use its synchronize feature a few times per day.

Writing your own synchronization routine can be a very big job.

>My company has several locations while the data in the tables should be updated, for say once a day, and the data may change either in the server and clients.
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>What should i do?
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>P.S. Since all our locations are in same area, i planned to use local phone rather than internet.
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>Please tell me what should i do?
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>Thanks in advance!
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>Aaron CHU