Fixes #63 use char semantic for varchar2 column

Author: PhilippSalvisberg

docs/4-language-usage/3-dml-and-sql/1-general/g-3170.md

@@ -16,7 +16,7 @@ Default values have been nullifiable until ORACLE 12c. Meaning any tool sending
 ```
 CREATE TABLE null_test (
    test_case        NUMBER(2) NOT NULL
-  ,column_defaulted VARCHAR2(10) DEFAULT 'Default')
+  ,column_defaulted VARCHAR2(10 CHAR) DEFAULT 'Default')
 /
 INSERT INTO null_test(test_case, column_defaulted) VALUES (1,'Value');
 INSERT INTO null_test(test_case, column_defaulted) VALUES (2,DEFAULT);
@@ -36,7 +36,7 @@ TEST_CASE  COLUMN_DEF
 ```
 CREATE TABLE null_test (
    test_case        NUMBER(2) NOT NULL
-  ,column_defaulted VARCHAR2(10) DEFAULT ON NULL 'Default')
+  ,column_defaulted VARCHAR2(10 CHAR) DEFAULT ON NULL 'Default')
 /
 INSERT INTO null_test(test_case, column_defaulted) VALUES (1,'Value');
 INSERT INTO null_test(test_case, column_defaulted) VALUES (2,DEFAULT);