I need to build some logic that requires me to iterate over table columns to query name, datatype etc.

Can I do this by querying the entity? Something like:

for each column in UserEntity.Columns

From your previous posts I assume you are using SelfServicing. You can achieve that this way:

foreach (EntityField f in new UserEntity().Fields)
{
    string theColumnName = f.SourceColumnName);
    ...
}