Wednesday, May 23
Compact Framework : Table Exist Method
In PDA based database applications one has to sometimes pull database/tables from the host machine/server onto the PDA (such as specific insurance agent's collection data). The procedure used is Remote Data Access (RDA). Compact framework has a stripped down version of the framework and some functionality available in the full framework isn't present on it.
I had a condition where I needed to I needed to check if a certain table existed on the pda database and if not then pull it from the server. I needed a table exist method and wanted to avoid the try catch code block which I have seen in use to derive that a table doesn't exist if you get a exception on something like this
'select (count(*) from premiums;'
I knew there would be a cleaner way to know if a table exist in a database or not.
Here is the method :
We query the meta data and get a clean answer, no try/catch needed derive the answer.
I had a condition where I needed to I needed to check if a certain table existed on the pda database and if not then pull it from the server. I needed a table exist method and wanted to avoid the try catch code block which I have seen in use to derive that a table doesn't exist if you get a exception on something like this
'select (count(*) from premiums;'
I knew there would be a cleaner way to know if a table exist in a database or not.
Here is the method :
We query the meta data and get a clean answer, no try/catch needed derive the answer.
430 ///
431 /// Queries the information schema to find whether a table exists or not
432 ///
433 ///
434 ///
435 private bool TableExists(string table)
436 {437 bool retAnswer = false;
438 try
439 {440 int exist = (int)ConnectionManager.DBInfoConnection.ExecuteScalar(
441 "SELECT count(*) FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_NAME='" + table + "'");
442 if (exist == 1)
443 retAnswer = true;
444 }445 catch (Exception ex)
446 {447 GenericLogger.Error("Could not query database for list of tables", ex);
448 }449 return retAnswer;
450 }Please ignore the non use of SqlParameters. I had to add this as a maintainence method in an
2-3 years old app and when you have to decide between your urge to make drastic(essential)
changes to a system and the number of hours that have been alotted
to this task, I think pragmatism wins.
# posted by K : Wednesday, May 23, 2007
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