diff --git a/scalasql/src/dialects/Dialect.scala b/scalasql/src/dialects/Dialect.scala
index 3490df5c..08ffeb0c 100644
--- a/scalasql/src/dialects/Dialect.scala
+++ b/scalasql/src/dialects/Dialect.scala
@@ -99,6 +99,7 @@ trait Dialect extends DialectTypeMappers {
       r.getObject(idx) match {
         case u: UUID => u
         case s: String => UUID.fromString(s)
+        case null => null
       }
     }
 
@@ -110,16 +111,29 @@ trait Dialect extends DialectTypeMappers {
   implicit def BytesType: TypeMapper[geny.Bytes] = new BytesType
   class BytesType extends TypeMapper[geny.Bytes] {
     def jdbcType = JDBCType.VARBINARY
-    def get(r: ResultSet, idx: Int) = new geny.Bytes(r.getBytes(idx))
-    def put(r: PreparedStatement, idx: Int, v: geny.Bytes) = r.setBytes(idx, v.array)
+    def get(r: ResultSet, idx: Int) = {
+      val bytes = r.getBytes(idx)
+      if (bytes == null) null
+      else new geny.Bytes(bytes)
+    }
+    def put(r: PreparedStatement, idx: Int, v: geny.Bytes) = {
+      val byteArray = if (v == null) null else v.array
+      r.setBytes(idx, byteArray)
+    }
   }
 
   implicit def UtilDateType: TypeMapper[java.util.Date] = new UtilDateType
   class UtilDateType extends TypeMapper[java.util.Date] {
     def jdbcType = JDBCType.TIMESTAMP
-    def get(r: ResultSet, idx: Int) = new java.util.Date(r.getTimestamp(idx).getTime)
-    def put(r: PreparedStatement, idx: Int, v: java.util.Date) =
-      r.setTimestamp(idx, new java.sql.Timestamp(v.getTime))
+    def get(r: ResultSet, idx: Int) = {
+      val ts = r.getTimestamp(idx)
+      if (ts == null) null
+      else new java.util.Date(ts.getTime)
+    }
+    def put(r: PreparedStatement, idx: Int, v: java.util.Date) = {
+      val time = if (v == null) null else new java.sql.Timestamp(v.getTime)
+      r.setTimestamp(idx, time)
+    }
   }
 
   implicit def LocalDateType: TypeMapper[LocalDate] = new LocalDateType
@@ -147,9 +161,15 @@ trait Dialect extends DialectTypeMappers {
   class ZonedDateTimeType extends TypeMapper[ZonedDateTime] {
     def jdbcType = JDBCType.TIMESTAMP_WITH_TIMEZONE
     override def castTypeString = "TIMESTAMP WITH TIME ZONE"
-    def get(r: ResultSet, idx: Int) = r.getTimestamp(idx).toInstant.atZone(ZoneId.systemDefault())
-    def put(r: PreparedStatement, idx: Int, v: ZonedDateTime) = r
-      .setTimestamp(idx, java.sql.Timestamp.from(v.toInstant))
+    def get(r: ResultSet, idx: Int) = {
+      val ts = r.getTimestamp(idx)
+      if (ts == null) null
+      else ts.toInstant.atZone(ZoneId.systemDefault())
+    }
+    def put(r: PreparedStatement, idx: Int, v: ZonedDateTime) = {
+      val ts = if (v == null) null else java.sql.Timestamp.from(v.toInstant)
+      r.setTimestamp(idx, ts)
+    }
   }
 
   implicit def InstantType: TypeMapper[Instant] = new InstantType
@@ -173,8 +193,10 @@ trait Dialect extends DialectTypeMappers {
       }
     }
 
-    def put(r: PreparedStatement, idx: Int, v: Instant) = r
-      .setTimestamp(idx, java.sql.Timestamp.from(v))
+    def put(r: PreparedStatement, idx: Int, v: Instant) = {
+      val ts = if (v == null) null else java.sql.Timestamp.from(v)
+      r.setTimestamp(idx, ts)
+    }
   }
 
   implicit def OffsetTimeType: TypeMapper[OffsetTime] = new OffsetTimeType
@@ -190,10 +212,13 @@ trait Dialect extends DialectTypeMappers {
     def jdbcType = JDBCType.TIMESTAMP_WITH_TIMEZONE
     override def castTypeString = "TIMESTAMP WITH TIME ZONE"
     def get(r: ResultSet, idx: Int) = {
-      r.getTimestamp(idx).toInstant.atOffset(OffsetDateTime.now().getOffset)
+      val ts = r.getTimestamp(idx)
+      if (ts == null) null
+      else ts.toInstant.atOffset(OffsetDateTime.now().getOffset)
     }
     def put(r: PreparedStatement, idx: Int, v: OffsetDateTime) = {
-      r.setTimestamp(idx, java.sql.Timestamp.from(v.toInstant))
+      val ts = if (v == null) null else java.sql.Timestamp.from(v.toInstant)
+      r.setTimestamp(idx, ts)
     }
   }
 
@@ -201,8 +226,13 @@ trait Dialect extends DialectTypeMappers {
     new EnumType[T]
   class EnumType[T](implicit constructor: String => T) extends TypeMapper[T] {
     def jdbcType: JDBCType = JDBCType.VARCHAR
-    def get(r: ResultSet, idx: Int): T = constructor(r.getString(idx))
-    def put(r: PreparedStatement, idx: Int, v: T) = r.setObject(idx, v, java.sql.Types.OTHER)
+    def get(r: ResultSet, idx: Int): T = {
+      val str = r.getString(idx)
+      if (str == null) null.asInstanceOf[T]
+      else constructor(str)
+    }
+    def put(r: PreparedStatement, idx: Int, v: T) =
+      r.setObject(idx, v, java.sql.Types.OTHER)
   }
 
   implicit def from(x: Byte): Expr[Byte] = Expr(x)