Fix CREATE TABLE enum default validation to return correct error type

Modified columndefault.go to detect enum data truncation errors and return
ErrInvalidColumnDefaultValue instead of ErrIncompatibleDefaultType to match
MySQL behavior exactly.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <[email protected]>

Author: elianddb

enginetest/queries/script_queries.go

@@ -8706,7 +8706,7 @@ where
 			},
 			{
 				Query:       "create table tt (e enum('a', 'b', 'c') default 0)",
-				ExpectedErr: sql.ErrIncompatibleDefaultType,
+				ExpectedErr: sql.ErrInvalidColumnDefaultValue,
 			},
 			{
 				Query: "create table et (e enum('a', 'b', '', 'c'));",

sql/columndefault.go

@@ -16,6 +16,7 @@ package sql
 
 import (
 	"fmt"
+	"strings"
 )
 
 // ColumnDefaultValue is an expression representing the default value of a column. May represent both a default literal
@@ -83,6 +84,10 @@ func (e *ColumnDefaultValue) Eval(ctx *Context, r Row) (interface{}, error) {
 	if e.OutType != nil {
 		var inRange ConvertInRange
 		if val, inRange, err = e.OutType.Convert(ctx, val); err != nil {
+			// For enum data truncation errors, return Invalid default value error to match MySQL
+			if strings.HasPrefix(e.OutType.String(), "enum(") && strings.Contains(err.Error(), "Data truncated for column") {
+				return nil, ErrInvalidColumnDefaultValue.New("(unknown)")
+			}
 			return nil, ErrIncompatibleDefaultType.New()
 		} else if !inRange {
 			return nil, ErrValueOutOfRange.New(val, e.OutType)
@@ -229,6 +234,10 @@ func (e *ColumnDefaultValue) CheckType(ctx *Context) error {
 		}
 		_, inRange, err := e.OutType.Convert(ctx, val)
 		if err != nil {
+			// For enum data truncation errors, return Invalid default value error to match MySQL
+			if strings.HasPrefix(e.OutType.String(), "enum(") && strings.Contains(err.Error(), "Data truncated for column") {
+				return ErrInvalidColumnDefaultValue.New("(unknown)")
+			}
 			return ErrIncompatibleDefaultType.Wrap(err)
 		} else if !inRange {
 			return ErrIncompatibleDefaultType.Wrap(ErrValueOutOfRange.New(val, e.Expr))