feat: support database comment

Author: caifengyin

parser/ast.go

@@ -1502,6 +1502,7 @@ type CreateDatabase struct {
 	IfNotExists  bool // true if 'IF NOT EXISTS' is specified
 	OnCluster    *ClusterClause
 	Engine       *EngineExpr
+	Comment      *StringLiteral
 }
 
 func (c *CreateDatabase) Pos() Pos {
@@ -1531,6 +1532,10 @@ func (c *CreateDatabase) String() string {
 		builder.WriteString(" ")
 		builder.WriteString(c.Engine.String())
 	}
+	if c.Comment != nil {
+		builder.WriteString(" COMMENT ")
+		builder.WriteString(c.Comment.String())
+	}
 	return builder.String()
 }
 

parser/parser_table.go

@@ -98,13 +98,18 @@ func (p *Parser) parseCreateDatabase(pos Pos) (*CreateDatabase, error) {
 	if engineExpr != nil {
 		StatementEnd = onCluster.End()
 	}
+	commentExpr, err := p.tryParseComment()
+	if err != nil {
+		return nil, err
+	}
 	return &CreateDatabase{
 		CreatePos:    pos,
 		StatementEnd: StatementEnd,
 		Name:         name,
 		IfNotExists:  ifNotExists,
 		OnCluster:    onCluster,
 		Engine:       engineExpr,
+		Comment:      commentExpr,
 	}, nil
 }