formula to find where there is no match for a string

I have a formula in Column C to make sure the SearchTerm and Customer material have the same number in the string. I need column D to make sure that the Search Term and Customer material has a base. Base is when the SearchTerm and Customer material are equal.

In the excel file the first data set does not have a base associated as it starts with an alt1 and MFG Obsoloete. It does not contain Customer material 0780 21 01. The second data set does have a base (0780 27 09 ST = 0780 27 09 Customer material.

I only want column D to indicate where there is no base.

Not exactly what I needed. I input your formula into column D.

The base item is when the ST=Customer material
Then, after the base it will have Needs Approvals/ALT (alternate) ect.

example:
SearchTerm Customer material
0215 08 22 0215 08 22
0215 08 22 0215 08 22 ALT
0215 08 22 0215 08 22 NEEDS APPROVAL4
**the first line is the base item. It needs to be there in order for there to have the second line ALT(alternate).

I need to find the line items that do not have a base item. For example the below:
SearchTerm Customer material
0780 27 01 0780 27 01 ALT1
0780 27 01 0780 27 01 MFG OBSOLETE


What this is a listing of universal parts. I am making sure that there is a base item (item always purchased) before there is alternates/needs approvals.

I want column D to call out where it has no base item.