Set table names to lower when creating table map

enginetest/queries/update_queries.go

@@ -692,6 +692,24 @@ t1.oid = t2.pid;`,
 			},
 		},
 	},
+	{
+		// https://github.com/dolthub/dolt/issues/10385
+		Name:    "UPDATE JOIN - tables with capitalized names",
+		Dialect: "mysql",
+		SetUpScript: []string{
+			"create table Items(ItemID char(38) NOT NULL primary key, Version int)",
+			"insert into Items values ('1234', 1)",
+			"create table Items2(ItemID char(38) NOT NULL primary key, Version int)",
+			"insert into Items2 values ('1234', 2)",
+			"UPDATE Items INNER JOIN Items2 ON (Items.ItemID = Items2.ItemID) SET Items.Version = Items2.Version WHERE Items.Version != Items2.Version",
+		},
+		Assertions: []ScriptTestAssertion{
+			{
+				Query:    "select * from Items",
+				Expected: []sql.Row{{"1234", 2}},
+			},
+		},
+	},
 }
 
 var SpatialUpdateTests = []WriteQueryTest{

sql/plan/update_join.go

@@ -235,23 +235,22 @@ func SplitRowIntoTableRowMap(row sql.Row, joinSchema sql.Schema) map[string]sql.
 		return ret
 	}
 
-	currentTable := joinSchema[0].Source
+	currentTable := strings.ToLower(joinSchema[0].Source)
 	currentRow := sql.Row{row[0]}
 
 	for i := 1; i < len(joinSchema); i++ {
 		c := joinSchema[i]
 
-		if c.Source != currentTable {
+		newTable := strings.ToLower(c.Source)
+		if newTable != currentTable {
 			ret[currentTable] = currentRow
-			currentTable = c.Source
+			currentTable = newTable
 			currentRow = sql.Row{row[i]}
 		} else {
-			currentTable = c.Source
 			currentRow = append(currentRow, row[i])
 		}
 	}
 
-	currentTable = strings.ToLower(currentTable)
 	ret[currentTable] = currentRow
 
 	return ret

sql/rowexec/update.go

@@ -232,7 +232,8 @@ func (u *updateJoinIter) Next(ctx *sql.Context) (sql.Row, error) {
 		tableToNewRowMap := plan.SplitRowIntoTableRowMap(newJoinRow, u.joinSchema)
 
 		for tableName, _ := range u.updaters {
-			oldTableRow := tableToOldRowMap[strings.ToLower(tableName)]
+			tableName = strings.ToLower(tableName)
+			oldTableRow := tableToOldRowMap[tableName]
 
 			// Handle the case of row being ignored due to it not being valid in the join row.
 			if isRightOrLeftJoin(u.joinNode) {