In WHERE clauses of the SELECT statement, you can use LONG VARCHAR columns only in IS NULL and IS NOT NULL expressions, in addition to the BIT_LENGTH, CHAR_LENGTH, CHAR_LENGTH64, CHARINDEX, LOCATE, OCTET_LENGTH, PATINDEX, SUBSTRING64, and SUBSTRING functions.
You can use the LIKE predicate to search for a pattern on a LONG VARCHAR column. All patterns of 126 or fewer characters are supported. Patterns longer than 254 characters are not supported. Some patterns between 127 and 254 characters in length are supported, depending on the contents of the pattern.
The LIKE predicate supports LONG VARCHAR (CLOB) variables of any size of data. Currently, a SQL variable can hold up to 2GB - 1 in length.
You cannot use LONG VARCHAR columns in the SELECT statement clauses ORDER BY, GROUP BY, and HAVING or with the DISTINCT keyword (SELECT DISTINCT and COUNT DISTINCT).