From 59eea3920d860f63f6506623688d26016cf5ff11 Mon Sep 17 00:00:00 2001
From: Scott Lepper <scott.lepper@gmail.com>
Date: Fri, 3 May 2024 14:52:13 +0100
Subject: [PATCH] sql expressions - Backport 87277 to v11.0.x (#87315)

sql expressions: improve parser (#87277)

(cherry picked from commit 1a2bbd61fd7c8c04befd8ef8a3f5c63aa494ca98)
---
 pkg/expr/sql/parser.go      | 77 +++++++++++++++++++++++++++++--------
 pkg/expr/sql/parser_test.go | 39 +++++++++++++++++++
 2 files changed, 100 insertions(+), 16 deletions(-)

diff --git a/pkg/expr/sql/parser.go b/pkg/expr/sql/parser.go
index 1ba6f9eee72..5aa3b07c577 100644
--- a/pkg/expr/sql/parser.go
+++ b/pkg/expr/sql/parser.go
@@ -24,21 +24,7 @@ func TablesList(rawSQL string) ([]string, error) {
 	switch kind := stmt.(type) {
 	case *sqlparser.Select:
 		for _, from := range kind.From {
-			buf := sqlparser.NewTrackedBuffer(nil)
-			from.Format(buf)
-			fromClause := buf.String()
-			upperFromClause := strings.ToUpper(fromClause)
-			if strings.Contains(upperFromClause, "JOIN") {
-				return extractTablesFrom(fromClause), nil
-			}
-			if upperFromClause != "DUAL" && !strings.HasPrefix(fromClause, "(") {
-				if strings.Contains(upperFromClause, " AS") {
-					name := stripAlias(fromClause)
-					tables = append(tables, name)
-					continue
-				}
-				tables = append(tables, fromClause)
-			}
+			tables = append(tables, getTables(from)...)
 		}
 	default:
 		return parseTables(rawSQL)
@@ -46,7 +32,66 @@ func TablesList(rawSQL string) ([]string, error) {
 	if len(tables) == 0 {
 		return parseTables(rawSQL)
 	}
-	return tables, nil
+	return validateTables(tables), nil
+}
+
+func validateTables(tables []string) []string {
+	validTables := []string{}
+	for _, table := range tables {
+		if strings.ToUpper(table) != "DUAL" {
+			validTables = append(validTables, table)
+		}
+	}
+	return validTables
+}
+
+func joinTables(join *sqlparser.JoinTableExpr) []string {
+	t := getTables(join.LeftExpr)
+	t = append(t, getTables(join.RightExpr)...)
+	return t
+}
+
+func getTables(te sqlparser.TableExpr) []string {
+	tables := []string{}
+	switch v := te.(type) {
+	case *sqlparser.AliasedTableExpr:
+		tables = append(tables, nodeValue(v.Expr))
+		return tables
+	case *sqlparser.JoinTableExpr:
+		tables = append(tables, joinTables(v)...)
+		return tables
+	case *sqlparser.ParenTableExpr:
+		for _, e := range v.Exprs {
+			tables = getTables(e)
+		}
+	default:
+		tables = append(tables, unknownExpr(te)...)
+	}
+	return tables
+}
+
+func unknownExpr(te sqlparser.TableExpr) []string {
+	tables := []string{}
+	fromClause := nodeValue(te)
+	upperFromClause := strings.ToUpper(fromClause)
+	if strings.Contains(upperFromClause, "JOIN") {
+		return extractTablesFrom(fromClause)
+	}
+	if upperFromClause != "DUAL" && !strings.HasPrefix(fromClause, "(") {
+		if strings.Contains(upperFromClause, " AS") {
+			name := stripAlias(fromClause)
+			tables = append(tables, name)
+			return tables
+		}
+		tables = append(tables, fromClause)
+	}
+	return tables
+}
+
+func nodeValue(node sqlparser.SQLNode) string {
+	buf := sqlparser.NewTrackedBuffer(nil)
+	node.Format(buf)
+	return buf.String()
 }
 
 func extractTablesFrom(stmt string) []string {
diff --git a/pkg/expr/sql/parser_test.go b/pkg/expr/sql/parser_test.go
index 200dd07195e..ca3b685e34b 100644
--- a/pkg/expr/sql/parser_test.go
+++ b/pkg/expr/sql/parser_test.go
@@ -89,3 +89,42 @@ func TestRightJoin(t *testing.T) {
 	assert.Equal(t, "A", tables[0])
 	assert.Equal(t, "B", tables[1])
 }
+
+func TestAliasWithJoin(t *testing.T) {
+	sql := `select * from A as X
+	RIGHT JOIN B ON A.name = X.name
+	LIMIT 10`
+	tables, err := TablesList((sql))
+	assert.Nil(t, err)
+
+	assert.Equal(t, 2, len(tables))
+	assert.Equal(t, "A", tables[0])
+	assert.Equal(t, "B", tables[1])
+}
+
+func TestAlias(t *testing.T) {
+	sql := `select * from A as X LIMIT 10`
+	tables, err := TablesList((sql))
+	assert.Nil(t, err)
+
+	assert.Equal(t, 1, len(tables))
+	assert.Equal(t, "A", tables[0])
+}
+
+func TestParens(t *testing.T) {
+	sql := `SELECT  t1.Col1,
+	t2.Col1,
+	t3.Col1
+	FROM    table1 AS t1
+	LEFT JOIN	(
+	table2 AS t2
+	INNER JOIN table3 AS t3 ON t3.Col1 = t2.Col1
+	) ON t2.Col1 = t1.Col1;`
+	tables, err := TablesList((sql))
+	assert.Nil(t, err)
+
+	assert.Equal(t, 3, len(tables))
+	assert.Equal(t, "table1", tables[0])
+	assert.Equal(t, "table2", tables[1])
+	assert.Equal(t, "table3", tables[2])
+}