DBNull if statement

Question

I m trying to execute a stored procedure and then use an if statement to check for null values and I m coming up short  I m a VB guy so please bear with me if I m making a schoolboy syntax error   objConn   new SqlConnection strConnection   objConn Open    objCmd   new SqlCommand strSQL  objConn   rsData   objCmd ExecuteReader    rsData Read     if    rsData  usr ursrdaystime   Equals System DBNull Value                          strLevel   rsData  usr ursrdaystime   ToString                 Would this allow me to check whether the SQL connection is returning just a value and if so then populating my string   I m used to being able to just check the below to see if a value is being returned and not sure I m doing it correctly with C   If Not IsDBNull rsData  usr ursrdaystime     Any help would be appreciated

User · Answer

The idiomatic way is to say   if rsData  usr ursrdaystime      DBNull Value        strLevel   rsData  usr ursrdaystime   ToString        This   rsData   objCmd ExecuteReader    rsData Read      Makes it look like you re reading exactly one value  Use IDbCommand ExecuteScalar instead

User · Answer

Ternary operator should do nicely here  condition   first expression   second expression        strLevel    Convert IsDBNull rsData  usr ursrdaystime      Convert ToString rsData  usr ursrdaystime      null

User · Answer

At first use ExecuteScalar   objConn   new SqlConnection strConnection    objConn Open     objCmd   new SqlCommand strSQL  objConn    object result   cmd ExecuteScalar     if result    null       strLevel        else       strLevel   result ToString

User · Answer

Consider   if rsData Read        int index   rsData GetOrdinal  columnName       I expect  just  ursrdaystime    if rsData IsDBNull index             is a null     else           access the value via any of the rsData Get  index  methods       else        no row returned     Also  you need more using  p

User · Answer

Yes  just a syntax problem  Try this instead   if  reader  usr ursrdaystime      DBNull Value     Equals   is checking to see if two Object instances are the same

User · Answer

if  rsData IsDBNull rsData GetOrdinal  usr ursrdaystime         strLevel   rsData GetString  usr ursrdaystime         http   msdn microsoft com en-us library system data sqlclient sqldatareader isdbnull aspx  http   msdn microsoft com en-us library system data sqlclient sqldatareader getordinal aspx

User · Answer

The closest equivalent to your VB would be  see this    Convert IsDBNull     But there are a number of ways to do this  and most are linked from here

User · Answer

I use String IsNullorEmpty often  It will work her because when DBNull is set to  ToString it returns empty     if   String IsNullorEmpty rsData  usr ursrdaystime   toString              strLevel   rsData  usr ursrdaystime   toString

User · Answer

This should work       if  rsData  usr ursrdaystime      System DBNull Value         strLevel   rsData  usr ursrdaystime   ToString        also need to add using statement  like bellow   using  var objConn   new SqlConnection strConnection                  objConn Open            using  var objCmd   new SqlCommand strSQL  objConn                        using  var rsData   objCmd ExecuteReader                               while  rsData Read                                     if  rsData  usr ursrdaystime      System DBNull Value                                         strLevel   rsData  usr ursrdaystime   ToString                                                                       this ll automaticly dispose  close  resources outside of block

[c#] DBNull if statement

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