fix: handle NULL primary key value with IS NULL in WHERE clause

Author: datlechin

TablePro/Core/Utilities/SQL/SQLRowToStatementConverter.swift

@@ -49,7 +49,11 @@ struct SQLRowToStatementConverter {
                 return "\(quoteColumn(col)) = \(formatValue(value))"
             }
             setClause = setClauses.joined(separator: ", ")
-            whereClause = "\(quoteColumn(pkColumn)) = \(formatValue(pkValue))"
+            if pkValue == nil {
+                whereClause = "\(quoteColumn(pkColumn)) IS NULL"
+            } else {
+                whereClause = "\(quoteColumn(pkColumn)) = \(formatValue(pkValue))"
+            }
         } else {
             let allClauses = columns.enumerated().map { index, col -> String in
                 let value = row.indices.contains(index) ? row[index] : nil

TableProTests/Core/Utilities/SQLRowToStatementConverterTests.swift

@@ -4,8 +4,8 @@
 //
 
 import Foundation
-import Testing
 @testable import TablePro
+import Testing
 
 @Suite("SQL Row To Statement Converter")
 struct SQLRowToStatementConverterTests {
@@ -92,6 +92,13 @@ struct SQLRowToStatementConverterTests {
         #expect(result == "UPDATE `users` SET `id` = '1', `name` = NULL, `email` = 'alice@example.com' WHERE `id` = '1' AND `name` IS NULL AND `email` = 'alice@example.com';")
     }
 
+    @Test("UPDATE with PK uses IS NULL in WHERE when PK value is NULL")
+    func updateNullPrimaryKeyValue() {
+        let converter = makeConverter()
+        let result = converter.generateUpdates(rows: [[nil, "Alice", "alice@example.com"]])
+        #expect(result == "UPDATE `users` SET `name` = 'Alice', `email` = 'alice@example.com' WHERE `id` IS NULL;")
+    }
+
     // MARK: - Database-Specific Quoting
 
     @Test("ClickHouse uses ALTER TABLE ... UPDATE syntax")
@@ -122,6 +129,15 @@ struct SQLRowToStatementConverterTests {
         #expect(result == "INSERT INTO `users` (`id`, `name`, `email`) VALUES ('1', 'Alice', 'alice@example.com');")
     }
 
+    @Test("DuckDB uses double-quote quoting and standard UPDATE syntax")
+    func duckdbUsesDoubleQuoteAndStandardUpdate() {
+        let converter = makeConverter(databaseType: .duckdb)
+        let insert = converter.generateInserts(rows: [["1", "Alice", "alice@example.com"]])
+        #expect(insert == "INSERT INTO \"users\" (\"id\", \"name\", \"email\") VALUES ('1', 'Alice', 'alice@example.com');")
+        let update = converter.generateUpdates(rows: [["1", "Alice", "alice@example.com"]])
+        #expect(update == "UPDATE \"users\" SET \"name\" = 'Alice', \"email\" = 'alice@example.com' WHERE \"id\" = '1';")
+    }
+
     // MARK: - Edge Cases
 
     @Test("Empty rows input returns empty string")