fix: s3 sql parse error for colums as with quotes (#18765)

internal/s3select/sql/parser.go

@@ -128,7 +128,7 @@ type JSONPath struct {
 // AliasedExpression is an expression that can be optionally named
 type AliasedExpression struct {
 	Expression *Expression `parser:"@@"`
-	As         string      `parser:"[ \"AS\" @Ident ]"`
+	As         string      `parser:"[ \"AS\" @Ident | \"AS\" @LitString ]"`
 }
 
 // Grammar for Expression

internal/s3select/sql/parser_test.go

@@ -383,3 +383,13 @@ func TestSqlLexerArithOps(t *testing.T) {
 	// 	fmt.Printf("%d: %#v\n", i, t)
 	// }
 }
+
+func TestParseSelectStatement(t *testing.T) {
+	exp, err := ParseSelectStatement("select _3,_1,_2 as 'mytest'  from S3object")
+	if err != nil {
+		t.Fatalf("parse alias sql error: %v", err)
+	}
+	if exp.selectAST.Expression.Expressions[2].As != "mytest" {
+		t.Fatalf("parse alias sql error: %s not equal %s", exp.selectAST.Expression.Expressions[2].As, err)
+	}
+}

internal/s3select/sql/statement.go

@@ -112,6 +112,14 @@ func ParseSelectStatement(s string) (stmt SelectStatement, err error) {
 
 	// Set table alias
 	stmt.tableAlias = selectAST.From.As
+	// Remove quotes from column aliases
+	if selectAST.Expression != nil {
+		for _, exp := range selectAST.Expression.Expressions {
+			if strings.HasSuffix(exp.As, "'") && strings.HasPrefix(exp.As, "'") && len(exp.As) >= 2 {
+				exp.As = exp.As[1 : len(exp.As)-1]
+			}
+		}
+	}
 	return
 }