hi, i am currently building an application that depends on a third party application written in .net using a mssql server database. i am more of a lamp guy and prefer mysql. to extend the application i would need to add some tables to the database. i am currently thinking of creating my custom tables in mysql instead of adding new tables to the mssql db. i currently have to use free tds to communicate with the mssql da and that creates some challenges. is it better to leave the third party application alone using free tds to communicate with it and then create a new mysql db for my tables or to just have all data in one database, namely mssql, and just use free tds to communicate with all data? i would have to write an api to communicate with the db and also prefer to have this in php rather than .net.

As long as you do not need to join tables between the two DBs, it's not a problem. The only disadvantage is the Managment of 2 DBs and extra connections but I don't foresee a noticeable performance issue because of it.

Not much experience in this, but better to convert all to mysql. Because 2 databse handeling may be difficult and also mssql doesn't not provide all functionality like mysql. e.g. you can not use limit in mssql.

better to convert all to mysql

Convert a third-party existing .net application to mysql...?? Hardly possible.

you can not use limit in mssql

It's called TOP. For paging there are other solutions too.

@pritaeas: downvote :( As a said i am not experienced but was facing issue for limit in one place.so shared.

The downvote was for the first comment, because that was clearly stated in the OP's question. It's just a downvote, no negative rep...