linq - C# string to number, TryParse returns true when Parse fails -

i have column in database (sql server) storing averages varchar.

values not valid numbers, can : 0, 12, 5.5, .4, 4.0, 6., 5.21428571428571428571428571428571428571, x, fail, or empty text.

when assigning variable linq, want display :

• success if average valid number , >= 4
• failed if average valid number , < 4
• the raw text if average not valid number

the code :

myresults = mydatacontext.mydbfunction() double note; in myresults select new mainreportmodel() {     id = a.id,     lastname = a.nom,     firstname = a.prenom,     average = a.moyenne,     result = double.tryparse(a.moyenne.trim(), numberstyles.number, cultureinfo.invariantculture, out note) ? (double.parse(a.moyenne.trim(), numberstyles.number, cultureinfo.invariantculture) < 4 ? "failed" : "success") : a.moyenne } 

but parse fails.

when replacing double.parse(a.moyenne.trim() hardcoded value (for example double.parse("3.3") works fine.

so seems 1 of values of a.moyenne.trim() causing parse fail.

how can fail if tryparse returned true?

edit : here error message :

could not translate expression 'value(myprojectweb.models.myprojectdatacontext).mydbfunction().select(a => new mainreportmodel() {id = a.id, lastname = a.nom, firstname = a.prenom, average = a.moyenne, result = iif(tryparse(a.moyenne.trim(), number, invoke(value(system.func`1[system.globalization.cultureinfo])), invoke(value(system.func`1[system.double]))), iif((parse(a.moyenne.trim(), number, invoke(value(system.func`1[system.globalization.cultureinfo]))) < 4), invoke(value(system.func`1[system.string])), "success"), ((a.moyenne) + "</span>"))})' sql , not treat local expression. 

you can't perform tryparse on sql server, if not doing further selection criteria, can try pulling data sql , parsing on client.

eg

myresults = mydatacontext.mydbfunction() double note;  var list =(from in myresults select new  {    a.id,    a.nom,    a.prenom,    a.moyenne, }).tolist();   var finalresults = (from in list   select new mainreportmodel() {    id = a.id,    lastname = a.nom,    firstname = a.prenom,    average = a.moyenne,    result = double.tryparse(a.moyenne.trim(), numberstyles.number,    cultureinfo.invariantculture, out note) ? (double.parse(a.moyenne.trim(), numberstyles.number, cultureinfo.invariantculture) < 4 ? "failed" : "success") : a.moyenne }