Bug #19498: Inconsistent support for DEFAULT in TEXT columns

  When a default of '' was specified for TEXT/BLOB columns, the specification
  was silently ignored. This is presumably to be nice to applications (or
  people) who generate their column definitions in a not-very-clever fashion.

  For clarity, doing this now results in a warning, or an error in strict
  mode.


mysql-test/r/federated.result:
  Update results
mysql-test/r/fulltext_distinct.result:
  Update results
mysql-test/r/fulltext_update.result:
  Update results
mysql-test/r/gis-rtree.result:
  Update results
mysql-test/r/gis.result:
  Update results
mysql-test/r/join_outer.result:
  Update results
mysql-test/r/order_by.result:
  Update results
mysql-test/r/type_blob.result:
  Add new results
mysql-test/r/type_ranges.result:
  Update results
mysql-test/t/type_blob.test:
  Add new test
sql/field.cc:
  Issue a warning when setting '' as the default on a BLOB/TEXT column,
  and make it an error in strict mode. Also, clarify comments about when
  NO_DEFAULT_VALUE_FLAG is set.

1 files changed, 19 insertions, 2 deletions

diff --git a/sql/field.cc b/sql/field.cc
index 946351efe36..31184a9f08c 100644
--- a/sql/field.cc
+++ b/sql/field.cc
@@ -8363,7 +8363,8 @@ bool create_field::init(THD *thd, char *fld_name, enum_field_types fld_type,
 
   comment= *fld_comment;
   /*
-    Set flag if this field doesn't have a default value
+    Set NO_DEFAULT_VALUE_FLAG if this field doesn't have a default value and
+    it is NOT NULL, not an AUTO_INCREMENT field and not a TIMESTAMP.
   */
   if (!fld_default_value && !(fld_type_modifier & AUTO_INCREMENT_FLAG) &&
       (fld_type_modifier & NOT_NULL_FLAG) && fld_type != FIELD_TYPE_TIMESTAMP)
@@ -8440,12 +8441,28 @@ bool create_field::init(THD *thd, char *fld_name, enum_field_types fld_type,
       /* Allow empty as default value. */
       String str,*res;
       res= fld_default_value->val_str(&str);
-      if (res->length())
+      /*
+        A default other than '' is always an error, and any non-NULL
+        specified default is an error in strict mode.
+      */
+      if (res->length() || (thd->variables.sql_mode &
+                            (MODE_STRICT_TRANS_TABLES |
+                             MODE_STRICT_ALL_TABLES)))
       {
         my_error(ER_BLOB_CANT_HAVE_DEFAULT, MYF(0),
                  fld_name); /* purecov: inspected */
         DBUG_RETURN(TRUE);
       }
+      else
+      {
+        /*
+          Otherwise a default of '' is just a warning.
+        */
+        push_warning_printf(thd, MYSQL_ERROR::WARN_LEVEL_WARN,
+                            ER_BLOB_CANT_HAVE_DEFAULT,
+                            ER(ER_BLOB_CANT_HAVE_DEFAULT),
+                            fld_name);
+      }
       def= 0;
     }
     flags|= BLOB_FLAG;