diff --git a/README.md b/README.md
index 0e27e50..7563aaa 100644
--- a/README.md
+++ b/README.md
@@ -1085,8 +1085,7 @@ func main() {
                 trdsql.NewImporter(trdsql.InDelimiter(":")),
                 trdsql.NewExporter(trdsql.NewWriter()),
         )
-        err := trd.Exec("SELECT c1 FROM /etc/passwd")
-        if err != nil {
+        if err := trd.Exec("SELECT c1 FROM /etc/passwd"); err != nil {
                 log.Fatal(err)
         }
 }
diff --git a/_example/simple/main.go b/_example/simple/main.go
index ff94b64..eea371d 100644
--- a/_example/simple/main.go
+++ b/_example/simple/main.go
@@ -12,8 +12,7 @@ func main() {
 		trdsql.NewImporter(trdsql.InDelimiter(":")),
 		trdsql.NewExporter(trdsql.NewWriter()),
 	)
-	err := trd.Exec("SELECT c1 FROM /etc/passwd")
-	if err != nil {
+	if err := trd.Exec("SELECT c1 FROM /etc/passwd"); err != nil {
 		log.Fatal(err)
 	}
 }
diff --git a/importer_buffer.go b/importer_buffer.go
index 991c70f..92f2d06 100644
--- a/importer_buffer.go
+++ b/importer_buffer.go
@@ -44,5 +44,5 @@ func (i *BufferImporter) ImportContext(ctx context.Context, db *DB, query string
 	if err := db.CreateTable(i.tableName, names, types, true); err != nil {
 		return query, err
 	}
-	return query, db.Import(i.tableName, names, i.Reader)
+	return query, db.ImportContext(ctx, i.tableName, names, i.Reader)
 }
diff --git a/importer_slice.go b/importer_slice.go
index bca1b62..55e181c 100644
--- a/importer_slice.go
+++ b/importer_slice.go
@@ -36,5 +36,5 @@ func (i *SliceImporter) ImportContext(ctx context.Context, db *DB, query string)
 	if err := db.CreateTable(i.tableName, names, types, true); err != nil {
 		return query, err
 	}
-	return query, db.Import(i.tableName, names, i.SliceReader)
+	return query, db.ImportContext(ctx, i.tableName, names, i.SliceReader)
 }
diff --git a/output_raw.go b/output_raw.go
index 5459a34..9fc9f51 100644
--- a/output_raw.go
+++ b/output_raw.go
@@ -17,13 +17,14 @@ type RAWWriter struct {
 
 // NewRAWWriter returns RAWWriter.
 func NewRAWWriter(writeOpts *WriteOpts) *RAWWriter {
-	var err error
-	w := &RAWWriter{}
-	w.writer = bufio.NewWriter(writeOpts.OutStream)
-	w.delimiter, err = strconv.Unquote(`"` + writeOpts.OutDelimiter + `"`)
+	delimiter, err := strconv.Unquote(`"` + writeOpts.OutDelimiter + `"`)
 	if err != nil {
 		debug.Printf("%s\n", err)
 	}
+
+	w := &RAWWriter{}
+	w.writer = bufio.NewWriter(writeOpts.OutStream)
+	w.delimiter = delimiter
 	w.outHeader = writeOpts.OutHeader
 	if writeOpts.OutUseCRLF {
 		w.endLine = "\r\n"
diff --git a/reader.go b/reader.go
index efec33b..01d0d9f 100644
--- a/reader.go
+++ b/reader.go
@@ -51,8 +51,12 @@ var readerFuncs = map[Format]ReaderFunc{
 	},
 }
 
-var extFormat Format = 100
-var registerMux = &sync.Mutex{}
+var (
+	// extFormat is the next format number to be assigned.
+	extFormat Format = 100
+	// registerMux is a mutex to protect access to the register.
+	registerMux = &sync.Mutex{}
+)
 
 func RegisterReaderFunc(ext string, readerFunc ReaderFunc) {
 	registerMux.Lock()
diff --git a/strings.go b/strings.go
index 32b93c5..7eb1ca9 100644
--- a/strings.go
+++ b/strings.go
@@ -9,7 +9,7 @@ import (
 )
 
 // ValString converts database value to string.
-func ValString(v interface{}) string {
+func ValString(v any) string {
 	switch t := v.(type) {
 	case nil:
 		return ""
@@ -33,7 +33,7 @@ func ValString(v interface{}) string {
 	}
 }
 
-func replaceNULL(nullString string, v interface{}) interface{} {
+func replaceNULL(nullString string, v any) any {
 	switch t := v.(type) {
 	case nil:
 		return nil
diff --git a/strings_test.go b/strings_test.go
index 0447adb..6c69439 100644
--- a/strings_test.go
+++ b/strings_test.go
@@ -8,7 +8,7 @@ import (
 
 func TestValString(t *testing.T) {
 	type args struct {
-		v interface{}
+		v any
 	}
 	tests := []struct {
 		name string
@@ -53,21 +53,21 @@ func TestValString(t *testing.T) {
 func Test_replaceNULL(t *testing.T) {
 	type args struct {
 		NULLString string
-		v          interface{}
+		v          any
 	}
 	tests := []struct {
 		name string
 		args args
-		want interface{}
+		want any
 	}{
 		{
 			name: "test1",
-			args: args{NULLString: "NULL", v: interface{}("N")},
+			args: args{NULLString: "NULL", v: any("N")},
 			want: "N",
 		},
 		{
 			name: "testMatch",
-			args: args{NULLString: "NULL", v: interface{}("NULL")},
+			args: args{NULLString: "NULL", v: any("NULL")},
 			want: nil,
 		},
 		{