parser: add NULL DEFINED BY and FORMAT to LOAD DATA (pingcap#41332)

ref pingcap#40499

parser/ast/dml.go

@@ -1814,17 +1814,20 @@ const (
 
 // LoadDataStmt is a statement to load data from a specified file, then insert this rows into an existing table.
 // See https://dev.mysql.com/doc/refman/5.7/en/load-data.html
-// in TiDB we extend the syntax to use LOAD DATA as a more general way to import data.
+// in TiDB we extend the syntax to use LOAD DATA as a more general way to import data, see
+// https://github.com/pingcap/tidb/issues/40499
 type LoadDataStmt struct {
 	dmlNode
 
 	FileLocRef        FileLocRefTp
 	Path              string
+	Format            string // empty only when it's CSV-like
 	OnDuplicate       OnDuplicateKeyHandlingType
 	Table             *TableName
 	Columns           []*ColumnName
 	FieldsInfo        *FieldsClause
 	LinesInfo         *LinesClause
+	NullInfo          *NullDefinedBy
 	IgnoreLines       uint64
 	ColumnAssignments []*Assignment
 
@@ -1841,6 +1844,10 @@ func (n *LoadDataStmt) Restore(ctx *format.RestoreCtx) error {
 	}
 	ctx.WriteKeyWord("INFILE ")
 	ctx.WriteString(n.Path)
+	if n.Format != "" {
+		ctx.WriteKeyWord(" FORMAT ")
+		ctx.WriteString(n.Format)
+	}
 	if n.OnDuplicate == OnDuplicateKeyHandlingReplace {
 		ctx.WriteKeyWord(" REPLACE")
 	} else if n.OnDuplicate == OnDuplicateKeyHandlingIgnore {
@@ -1850,8 +1857,15 @@ func (n *LoadDataStmt) Restore(ctx *format.RestoreCtx) error {
 	if err := n.Table.Restore(ctx); err != nil {
 		return errors.Annotate(err, "An error occurred while restore LoadDataStmt.Table")
 	}
-	n.FieldsInfo.Restore(ctx)
-	n.LinesInfo.Restore(ctx)
+	if n.FieldsInfo != nil {
+		n.FieldsInfo.Restore(ctx)
+	}
+	if n.LinesInfo != nil {
+		n.LinesInfo.Restore(ctx)
+	}
+	if n.NullInfo != nil {
+		n.NullInfo.Restore(ctx)
+	}
 	if n.IgnoreLines != 0 {
 		ctx.WriteKeyWord(" IGNORE ")
 		ctx.WritePlainf("%d", n.IgnoreLines)
@@ -1993,6 +2007,21 @@ func (n *LinesClause) Restore(ctx *format.RestoreCtx) error {
 	return nil
 }
 
+// NullDefinedBy represent a syntax that extends MySQL's standard
+type NullDefinedBy struct {
+	NullDef     string
+	OptEnclosed bool
+}
+
+// Restore for NullDefinedBy
+func (n *NullDefinedBy) Restore(ctx *format.RestoreCtx) {
+	ctx.WriteKeyWord(" NULL DEFINED BY ")
+	ctx.WriteString(n.NullDef)
+	if n.OptEnclosed {
+		ctx.WriteKeyWord(" OPTIONALLY ENCLOSED")
+	}
+}
+
 // CallStmt represents a call procedure query node.
 // See https://dev.mysql.com/doc/refman/5.7/en/call.html
 type CallStmt struct {

parser/misc.go

@@ -284,6 +284,7 @@ var tokenMap = map[string]int{
 	"DEC":                      decimalType,
 	"DECIMAL":                  decimalType,
 	"DEFAULT":                  defaultKwd,
+	"DEFINED":                  defined,
 	"DEFINER":                  definer,
 	"DELAY_KEY_WRITE":          delayKeyWrite,
 	"DELAYED":                  delayed,