String Functions and Operators If the file does not exist or cannot be read because one of the preceding conditions is not satisfied, the function returns  NULL . The  character_set_filesystem  system variable controls interpretation of file names that are given as literal strings. mysql>  UPDATE t SET blob_col=LOAD_FILE(’/tmp/picture’) WHERE id=1; • LOCATE( substr , str ) ,  LOCATE( substr , str , pos ) The first syntax returns the position of the first occurrence of substring  substr  in string  str . The second syntax returns the position of the first occurrence of substring  substr  in string  str , starting at position  pos . Returns  0  if  substr  is not in  str . Returns  NULL  if any argument is  NULL . This function is multibyte safe, and is case-sensitive only if at least one argument is a binary string. Returns the string  str  with all characters changed to lowercase according to the current character set mapping. The default is  utf8mb4 . LOWER()  (and  UPPER() ) are ineffective when applied to binary strings ( BINARY ,  VARBINARY ,  BLOB ). To perform lettercase conversion of a binary string, first convert it to a nonbinary string using a character set appropriate for the data stored in the string: For collations of Unicode character sets,  LOWER()  and  UPPER()  work according to the Unicode Collation Algorithm (UCA) version in the collation name, if there is one, and UCA 4.0.0 if no version is specified. For example,  utf8mb4_0900_ai_ci  and  utf8_unicode_520_ci  work according to UCA 9.0.0 and 5.2.0, respectively, whereas  utf8_unicode_ci  works according to UCA 4.0.0. See Section 10.10.1, “Unicode Character Sets” . This function is multibyte safe. LCASE()  used within views is rewritten as  LOWER() . 2178 mysql>  SET @str = BINARY ’New York’; mysql>  SELECT LOWER(@str), LOWER(CONVERT(@str USING utf8mb4)); +-------------+------------------------------------+ | LOWER(@str) | LOWER(CONVERT(@str USING utf8mb4)) | +-------------+------------------------------------+ | New York | new york | +-------------+------------------------------------+ mysql>  SELECT LOWER(’QUADRATICALLY’); -> ’quadratically’ mysql>  SELECT LOCATE(’bar’, ’foobarbar’); -> 4 mysql>  SELECT LOCATE(’xbar’, ’foobar’); -> 0 mysql>  SELECT LOCATE(’bar’, ’foobarbar’, 5); -> 7 • LOWER( str )