The CHARINDEX function returns a 64-bit signed integer containing the position of the first occurrence of the specified string in the large object column or variable parameter. For CHAR and VARCHAR columns, CHARINDEX returns a 32-bit signed integer position.
string-expression – the string of up to 255 bytes, for which you are searching.
large-object-column – the name of the LONG VARCHAR or LONG BINARY column or variable.
All the positions or offsets, returned or specified, in the CHARINDEX function are always character offsets and may be different from the byte offset for multibyte data.
If the large object cell being searched contains more than one instance of string-expression, CHARINDEX returns only the position of the first instance.
If the column does not contain the string, the CHARINDEX function returns zero (0).
Searching for a string longer than 255 bytes returns NULL.
Searching for a zero-length string returns 1.
If any of the arguments is NULL, the result is NULL.
CHARINDEX supports searching LONG VARCHAR and LONG BINARY columns and LONG VARCHAR and LONG BINARY variables of any size of data. Currently, a SQL variable can hold up to 2GB - 1 in length.