[dehlerm]

While starting to explore the DBMS features of PyS60 I ran into a problem I can't solve. When I write and then read float values to a database the decimal places seem to be truncated and only the integer places plus '.0' are shown. E.g. '123.0' appears instead of the stored '123.123'.
The code below creates a database and fills it with some float values and there string representations. Then the stored values are printed out.
In the printout the problem, hopefully, becomes visible.

Any help is appreciated
Thanks Martin

import e32db

db_name = u"c:\\test.db"

#create/open database
try:
	db = e32db.Dbms()
	db.open(db_name)
except:
	db.create(db_name)
	db.open(db_name)
	sql_create = u"CREATE TABLE test (value FLOAT, string VARCHAR)"
	db.execute(sql_create)

#delete all data in table test
sql_del = u"DELETE FROM test"
db.execute(sql_del)

#write data to database
for x in range(10):
	value = x * 123.123
	string = unicode(x * 123.123)
	sql_add = "INSERT INTO test (value, string) VALUES (%d,'%s')"%(value, string)
	db.execute(sql_add)

#read and print out data
dbv = e32db.Db_view()
dbv.prepare(db, u"SELECT * from test")
dbv.first_line()
print "float", "string"
for i in range(dbv.count_line()):
	dbv.get_line()
	print dbv.col(1), dbv.col(2)
	dbv.next_line()

db.compact()
db.close()

[nlsp]

Originally Posted by dehlerm

    sql_add = "INSERT INTO test (value, string) VALUES (%d,'%s')"%(value, string)

I'd say your problem is you use python string format %d for the float value. Try %f instead.

[dehlerm]

Originally Posted by nlsp

I'd say your problem is you use python string format %d for the float value. Try %f instead.

Thanks for your repy nlsp. But, %f doesn't work... -> KErrArgument error.

I also tried to specify the field which should store the float as DOUBLE or DOUBLE PRECISION in the CREATE statement (referring to table 7.1 of the PyS60 docu). This also doesn't solve the problem.

Anyone with more ideas?

[janekw_]

Try %e. It works, although it's pita when you have to provide literals.

[dehlerm]

Thanks for the solution janekw_!

I tried to figure out how it might work by examening the Nokia 'sports diary' example code and google e.g. http://snippets.dzone.com/posts/show/1616. Both were misleading in this case ;-).
Where can i find a documentation for such problems? Is it Python or SQL specific?

[janekw_]

You can find many useful info in Symbian SDK docs in DBMS section. PyS60 e32db is a very thin wrapper over native API. But in this case I just guessed right You can't give up precision (which you do with %d), you can't use decimal representation (%f) so the only option left was expotential representation.