Nested in SQL Server

In the SQL string is a single quotation mark as the delimiter, preceded by a string and followed by a single quotation mark. But the string can also contain single quotation marks, in order for the parser to distinguish between single quotes or delimiters in a string. Specifies that when single quotation marks appear in a string, a single quotation mark is added before it as a distinction. That is, in a single quotation-delimited string, two consecutive single quotation marks ' denote a single quote character.
The last four consecutive single quote boundaries are:
The first single quotation mark, the start delimiter for the string.
Next successive two single quotes, representing the value of the string (a single quotation mark)
The fourth single quotation mark, the ending delimiter of the string.

Nested in SQL Server