The binary Collation Compared to _bin Collations •When assigning column values for  INSERT  or  UPDATE  using a string literal: •When sending results from the server to a client: •Most MySQL collations have a pad attribute of  PAD SPACE . •The Unicode collations based on UCA 9.0.0 and higher have a pad attribute of  NO PAD ; see Section 10.10.1, “Unicode Character Sets” . •For  PAD SPACE  collations, trailing spaces are insignificant in comparisons; strings are compared without regard to trailing spaces. • NO PAD  collations treat trailing spaces as significant in comparisons, like any other character. 1957 mysql>  SELECT COLLATION_NAME, PAD_ATTRIBUTE FROM INFORMATION_SCHEMA.COLLATIONS The differing behaviors can be demonstrated using the two  utf8mb4  binary collations, one of which is  PAD SPACE , the other of which is  NO PAD . The example also shows how to use the  INFORMATION_SCHEMA COLLATIONS  table to determine the pad attribute for collations. For nonbinary strings ( CHAR ,  VARCHAR , and  TEXT  values), the string collation pad attribute determines treatment in comparisons of trailing spaces at the end of strings: MySQL collations have a pad attribute, which has a value of  PAD SPACE  or  NO PAD : Trailing Space Handling in Comparisons mysql>  SET NAMES binary; mysql>  SELECT LOWER(’aA’), LOWER(CONVERT(’aA’ USING utf8mb4)); +-------------+------------------------------------+ | LOWER(’aA’) | LOWER(CONVERT(’aA’ USING utf8mb4)) | +-------------+------------------------------------+ | aA | aa | +-------------+------------------------------------+ mysql>  SET NAMES utf8mb4 COLLATE utf8mb4_bin; mysql>  SELECT LOWER(’aA’), UPPER(’zZ’); +-------------+-------------+ | LOWER(’aA’) | UPPER(’zZ’) | +-------------+-------------+ | aa | ZZ | +-------------+-------------+ The concept of lettercase does not apply to bytes in a binary string. To perform lettercase conversion, the string must first be converted to a nonbinary string using a character set appropriate for the data stored in the string: For binary string columns, no conversion occurs. For cases similar to those preceding, the string value is copied byte-wise. Collations for nonbinary character sets provide information about lettercase of characters, so characters in a nonbinary string can be converted from one lettercase to another, even for  _bin  collations that ignore lettercase for ordering: Lettercase Conversion SET NAMES latin1; SELECT utf8_bin_column FROM t2; SET NAMES latin1; INSERT INTO t1 (utf8_bin_column) VALUES (’string-in-latin1’);