fix(data-types/blob): only return null for mysql binary null (#9441)

lib/dialects/mysql/data-types.js

@@ -36,22 +36,6 @@ module.exports = BaseTypes => {
   BaseTypes.GEOMETRY.types.mysql = ['GEOMETRY'];
   BaseTypes.GEOMETRY.types.mysql = ['GEOMETRY'];
   BaseTypes.JSON.types.mysql = ['JSON'];
   BaseTypes.JSON.types.mysql = ['JSON'];
 
 
-  function BLOB(length) {
-    if (!(this instanceof BLOB)) return new BLOB(length);
-    BaseTypes.BLOB.apply(this, arguments);
-  }
-  inherits(BLOB, BaseTypes.BLOB);
-
-  BLOB.parse = function(value, options, next) {
-    const data = next();
-
-    if (Buffer.isBuffer(data) && data.length === 0) {
-      return null;
-    }
-
-    return data;
-  };
-
   function DECIMAL(precision, scale) {
   function DECIMAL(precision, scale) {
     if (!(this instanceof DECIMAL)) return new DECIMAL(precision, scale);
     if (!(this instanceof DECIMAL)) return new DECIMAL(precision, scale);
     BaseTypes.DECIMAL.apply(this, arguments);
     BaseTypes.DECIMAL.apply(this, arguments);
@@ -195,7 +179,6 @@ module.exports = BaseTypes => {
     UUID,
     UUID,
     GEOMETRY,
     GEOMETRY,
     DECIMAL,
     DECIMAL,
-    BLOB,
     JSON: JSONTYPE
     JSON: JSONTYPE
   };
   };