fix data type "interval year to month" code spelling

Author: sjjian

lexer.go

@@ -235,7 +235,7 @@ var unReservedKeyword = map[string]int{
 	"metadata":                _metadata,
 	"minextents":              _minextents,
 	"minvalue":                _minvalue,
-	"mouth":                   _mouth,
+	"month":                   _month,
 	"multivalue":              _multivalue,
 	"national":                _national,
 	"nchar":                   _nchar,

sql.go

@@ -185,7 +185,7 @@ func nextQuery(yylex interface{}) string {
     _metadata
     _minextents
     _minvalue
-    _mouth
+    _month
     _multivalue
     _national
     _nchar
@@ -541,7 +541,7 @@ UnReservedKeyword:
 |   _metadata
 |   _minextents
 |   _minvalue
-|   _mouth
+|   _month
 |   _multivalue
 |   _national
 |   _nchar
@@ -1908,13 +1908,13 @@ DatetimeDataTypes:
         d.SetDataDef(element.DataDefTimestamp)
         $$ = d
     }
-|   _interval _year _to _mouth
+|   _interval _year _to _month
     {
         d := &element.IntervalYear{}
         d.SetDataDef(element.DataDefIntervalYear)
         $$ = d
     }
-|   _interval _year '(' _intNumber ')' _to _mouth
+|   _interval _year '(' _intNumber ')' _to _month
     {
         precision := $4
         d := &element.IntervalYear{Precision: &precision}

sql.y

@@ -24,4 +24,8 @@ CREATE TABLE test."persons" ( NUMERIC_NAME NUMERIC ( 15, 2 ), Decimal_NAME DECIM
 
 create table TEST.T21 (t CHAR(255));
 
-create table TEST.T21 (t character(255));
+create table TEST.T21 (t character(255));
+
+CREATE TABLE TEST.INTERVAL_YEAR_COLUMNS(ID INT, C_INTERVAL_YEAR INTERVAL YEAR TO MONTH);
+
+CREATE TABLE TEST.INTERVAL_YEAR_COLUMNS(ID INT, C_INTERVAL_YEAR INTERVAL YEAR(3) TO MONTH);