Bug#18908: ERROR 1406 (22001): Data too long for column :: using utf8

Problem: Too confusing error message when cannot convert
between string and column character sets on INSERT and UPDATE.
Fix: producing a better error message, instead of "Data too long"
in such cases
Additional changes: Adding "DROP TABLE IF EXISTS" into several
tests to be safe against failures in previous tests. 


mysql-test/include/strict_autoinc.inc:
  Adding DROP TABLE to be safe against previous tests failure.
mysql-test/r/ctype_recoding.result:
  Fixing test results
mysql-test/r/ctype_utf8.result:
  Fixing test results
mysql-test/r/fulltext.result:
  Fixing test results
mysql-test/r/strict_autoinc_1myisam.result:
  Adding DROP TABLE to be safe against previous tests failure.
mysql-test/r/strict_autoinc_2innodb.result:
  Adding DROP TABLE to be safe against previous tests failure.
mysql-test/r/strict_autoinc_3heap.result:
  Adding DROP TABLE to be safe against previous tests failure.
mysql-test/r/strict_autoinc_4bdb.result:
  Adding DROP TABLE to be safe against previous tests failure.
mysql-test/r/strict_autoinc_5ndb.result:
  Adding DROP TABLE to be safe against previous tests failure.
sql/field.cc:
  - producing better error messages than
    "DATA TRUNCATED" or "DATA TOO LONG" (in strict mode)
    in case of "not well formed source" and
    "cannot convert to field character set"
  - Performance improvements: copying directly to
    the target, instead of using an intermediate
    String.
  - Moving duplicate code into report_data_too_long() function.
sql/sql_string.cc:
  Adding a new function to convert strings between character sets,
  but not more than "nchar" characters - a helper function for
  Field_string::store(), Field_varstring::store() and Field_blob::store().
sql/sql_string.h:
  Adding new function prototype.

1 files changed, 8 insertions, 0 deletions

diff --git a/sql/sql_string.h b/sql/sql_string.h
index 0659f684afe..09b8478adf8 100644
--- a/sql/sql_string.h
+++ b/sql/sql_string.h
@@ -32,6 +32,14 @@ String *copy_if_not_alloced(String *a,String *b,uint32 arg_length);
 uint32 copy_and_convert(char *to, uint32 to_length, CHARSET_INFO *to_cs,
 			const char *from, uint32 from_length,
 			CHARSET_INFO *from_cs, uint *errors);
+uint32 well_formed_copy_nchars(CHARSET_INFO *to_cs,
+                               char *to, uint to_length,
+                               CHARSET_INFO *from_cs,
+                               const char *from, uint from_length,
+                               uint nchars,
+                               const char **well_formed_error_pos,
+                               const char **cannot_convert_error_pos,
+                               const char **from_end_pos);
 
 class String
 {