Question

What is the best way of inserting a datetime value using a dynamic sql string, whilst at the same time being able to handle the possibility of the value being null?

The current statement inserts into a table from a select statement built using a string. The datetime value is stored in a parameter and the parameter is used in the select.

Like so:

SET @execsql = 'INSERT INTO ( start_date )
SELECT ( ''' + CAST(start_date as VARCHAR) + ''' + ')'
EXECUTE(@execsql)

Answer 1

As you’re running Sybase something like

Set @execsql = 'Insert Into <table> ( start_date ) Select (' + 
  Case When start_date is null Then
    'Null' 
  Else 
    '''' + Cast(start_date as Varchar) + '''' 
  End + ')'

Execute(@execsql)

Should do the trick

Here’s the SQL Server way for reference

Declare @sql nvarchar(max), @params navarchar(max)

Set @sql = N'Insert Into Table (start_date) Select (@start_date)'
Set @params = N'@start_date datetime'

Exec sp_executesql @sql, @params, @start_date

Obviously, in this case you wouldn’t need dynamic SQL, but I assume this is part of a larger example.

As always with dynamic SQL questions, http://www.sommarskog.se/dynamic_sql.html is recommended reading.