Currently I have varchar field. The delimiter is "$P$P$".

The delimiter will appear at least once and at most twice in the varchar data.

Eg.

Sample Heading$P$P$Sample description$P$P$Sample conclusion

Sample Heading$P$P$Sample Description

If the delimiter appears twice, I need to insert a text before the second occurance of the delimiter.

Eg:

Sample Heading$P$P$Sample DescriptionINSERT TEXT HERE$P$P$Sample Conclusion

If the delimiter occurs only once, then I need to insert a text at the end of the field.

Eg:

Sample Heading$P$P$Sample DescriptionAPPEND TEXT HERE

How this can be done in SQL query?