SQLite Min，Max在ado.net中返回错误结果

Question

i am using ADO.NET Data Provider for SQLite: 1.0.82.0

Aggregate function returns wrong result:

###Table structure###
CREATE TABLE ta85 (id INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT, date INTEGER, _90 REAL, _100 REAL)

###Rows: ###
select * from ta85

id, date, _90, _100

"1","1355480577920","4,4","2"

"2","1355480877929","15","5,2"

"3","1355481177937","26,4","9,4"

------------------

Now if i want to select the max, min values for each column:

SELECT date,MIN(_90), MAX(_90),MIN(_100), MAX(_100) FROM ta85 WHERE date between 1355480296794 and 1355481366266

returns:

"1355481177937","15","4,4","2","9,4" 

which for column _100 is correct but for column _90 is wrong.

Solution

Thanks for all your answers. you were both right.

cmd.Parameters.AddWithValue(columname,"");

to

cmd.Parameters.AddWithValue(columname,0.0d);

Answer 1

You're using the wrong kind of literal to insert floating point numbers into the database, and you're getting string comparisons. Use dots instead of commas.

Remember that SQLite is very loose with types :

SQLite uses a more general dynamic type system. In SQLite, the datatype of a value is associated with the value itself, not with its container.

SQL Fiddle here .

Answer 2

It appears you are comparing strings instead of numbers. Perhaps format your number as '4.4' instead of the '4,4'