Revert to old error and remove MySQL 8.4.5 error

- Use original ErrForeignKeyChildViolation error instead of MySQL 8.4.5 specific error
- Remove ErrForeignKeyChildViolationMySQL845 from error definitions and case statements
- Update tests to use old error
- Fix error message to include proper row data by passing row to validateDecimalConstraints
- Ensure error messages contain correct foreign key violation information

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

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

Author: elianddb

enginetest/queries/script_queries.go

@@ -10538,7 +10538,7 @@ where
 			},
 			{
 				Query:       "insert into child_dec_4_1 values (78.9);",
-				ExpectedErr: sql.ErrForeignKeyChildViolationMySQL845,
+				ExpectedErr: sql.ErrForeignKeyChildViolation,
 			},
 
 			{
@@ -10561,7 +10561,7 @@ where
 			},
 			{
 				Query:       "insert into child_dec_65_30 values (1.23);",
-				ExpectedErr: sql.ErrForeignKeyChildViolationMySQL845,
+				ExpectedErr: sql.ErrForeignKeyChildViolation,
 			},
 			{
 				Query:       "insert into child_dec_4_2 values (99.99);",

sql/errors.go

@@ -419,8 +419,7 @@ var (
 	ErrInsertIntoNonNullableProvidedNull = errors.NewKind("column name '%v' is non-nullable but attempted to set a value of null")
 
 	// ErrForeignKeyChildViolation is called when a rows is added but there is no parent row, and a foreign key constraint fails. Add the parent row first.
-	ErrForeignKeyChildViolation         = errors.NewKind("cannot add or update a child row - Foreign key violation on fk: `%s`, table: `%s`, referenced table: `%s`, key: `%s`")
-	ErrForeignKeyChildViolationMySQL845 = errors.NewKind("cannot add or update a child row: a foreign key constraint fails (`%s`.`%s`, CONSTRAINT `%s` FOREIGN KEY (`%s`) REFERENCES `%s` (`%s`))")
+	ErrForeignKeyChildViolation = errors.NewKind("cannot add or update a child row - Foreign key violation on fk: `%s`, table: `%s`, referenced table: `%s`, key: `%s`")
 
 	// ErrForeignKeyParentViolation is called when a parent row that is deleted has children, and a foreign key constraint fails. Delete the children first.
 	ErrForeignKeyParentViolation = errors.NewKind("cannot delete or update a parent row - Foreign key violation on fk: `%s`, table: `%s`, referenced table: `%s`, key: `%s`")
@@ -982,7 +981,6 @@ func CastSQLError(err error) *mysql.SQLError {
 		code = mysql.ERDupEntry
 	case ErrPartitionNotFound.Is(err):
 		code = 1526 // TODO: Needs to be added to vitess
-	case ErrForeignKeyChildViolationMySQL845.Is(err):
 	case ErrForeignKeyChildViolation.Is(err):
 		code = mysql.ErNoReferencedRow2 // test with mysql returns 1452 vs 1216
 	case ErrForeignKeyParentViolation.Is(err):

sql/plan/foreign_key_editor.go

@@ -513,7 +513,7 @@ func (reference *ForeignKeyReferenceHandler) CheckReference(ctx *sql.Context, ro
 	}
 	if err == nil {
 		// We have a parent row, but check for type-specific validation
-		if validationErr := reference.validateDecimalConstraints(); validationErr != nil {
+		if validationErr := reference.validateDecimalConstraints(row); validationErr != nil {
 			return validationErr
 		}
 		// We have a parent row so throw no error
@@ -544,7 +544,7 @@ func (reference *ForeignKeyReferenceHandler) CheckReference(ctx *sql.Context, ro
 }
 
 // validateDecimalConstraints checks that decimal foreign key columns have compatible scales.
-func (reference *ForeignKeyReferenceHandler) validateDecimalConstraints() error {
+func (reference *ForeignKeyReferenceHandler) validateDecimalConstraints(row sql.Row) error {
 	if reference.RowMapper.Index == nil {
 		return nil
 	}
@@ -563,9 +563,8 @@ func (reference *ForeignKeyReferenceHandler) validateDecimalConstraints() error
 		if childDecimal, ok := childType.(sql.DecimalType); ok {
 			if parentDecimal, ok := parentType.(sql.DecimalType); ok {
 				if childDecimal.Scale() != parentDecimal.Scale() {
-					return sql.ErrForeignKeyChildViolationMySQL845.New(reference.ForeignKey.Database, reference.ForeignKey.Table,
-						reference.ForeignKey.Name, strings.Join(reference.ForeignKey.Columns, ", "),
-						reference.ForeignKey.ParentTable, strings.Join(reference.ForeignKey.ParentColumns, ", "))
+					return sql.ErrForeignKeyChildViolation.New(reference.ForeignKey.Name, reference.ForeignKey.Table,
+						reference.ForeignKey.ParentTable, reference.RowMapper.GetKeyString(row))
 				}
 			}
 		}