c# - Properly check if a record already exists in a database -

c# - Properly check if a record already exists in a database -

i have read other questions on this, not help part. trying check if file has been uploaded(filename sent table) before creating record , allowing them upload same file again.

i using code , keeps telling me every file new file, when utilize same file testing. should result in "exists". connection established using "this.master.conn" please no sqlcommand stuff.

i tried using wildcards in query.

private string sqlcheck(string filename) { string check = "select videourl trainingvideo2 videourl '" + filename +"' , status=1;"; object ob = this.master.conn.executesqlscalarcommand(check); string result; if (dbnull.value.equals(ob)) { result = "exists"; } else { result = "newfile"; } homecoming result; }

also, have better(more efficient) way of doing this?

trying rewrite in c#.

private function checkname(name string) int32 dim sql string = "select id company name '" & name & "' " dim ob object = conn.executesqlscalarcommand(sql) if isdbnull(ob) homecoming 0 else homecoming cint(ob) end if end function

there new , more innovative methods devised around simple "replace ` , " characters ..." sql injection prevention techniques. in case, if videourl happens varchar (and not nvarchar), using unicode character u+02bc (url encoded = %ca%bc) pass in quote character unicode string, bypass c# checks, sql server conveniently convert quote character in query. 1 illustration of why should not doing :).

in terms of check, prefer using top 1 allow sql server cutting potential table scan short. so, utilize query:

select top 1 somenonnullintcolumn trainingvideo2 videourl ... , status=1;

execute query executescalar. if result null, record not exist.

c# asp.net sql-server