You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: sqlserver.go
    path of file: ./repos/usql/drivers/sqlserver
    
    the code of the file until where you have to start completion: // Package sqlserver defines and registers usql's Microsoft SQL Server driver.
//
// See: https://github.com/microsoft/go-mssqldb
// Group: base
package sqlserver

import (
	"context"
	"database/sql"
	"fmt"
	"io"
	"strconv"
	"strings"

	mssql "github.com/microsoft/go-mssqldb"
	sqlserver "github.com/microsoft/go-mssqldb" // DRIVER
	"github.com/xo/usql/drivers"
	"github.com/xo/usql/drivers/metadata"

	// needed for azuresql authentication, named pipes, and shared memory transport protocols
	_ "github.com/microsoft/go-mssqldb/azuread"
	_ "github.com/microsoft/go-mssqldb/namedpipe"
	_ "github.com/microsoft/go-mssqldb/sharedmemory"
)

func init() {
	drivers.Register("sqlserver", drivers.Driver{
		AllowMultilineComments:  true,
		RequirePreviousPassword: true,
		LexerName:               "tsql",
		/*
			// NOTE: this has been commented out, as it is not necessary. if
			// NOTE: the azuread.DriverName is changed from `azuresql`, then
			// NOTE: this func will be necessary as dburl will never import non
			// NOTE: stdlib package. as is, dburl.Open will handle the call
			// NOTE: to sql.Open and will pass the `azuresql` driver name
			Open: func(_ context.Context, u *dburl.URL, _, _ func() io.Writer) (func(string, string) (*sql.DB, error), error) {
				return func(_ string, params string) (*sql.DB, error) {
					driver := "sqlserver"
					switch {
					case u.Query().Has("fedauth"),
						strings.Contains(strings.ToLower(u.OriginalScheme), "azuresql"):
						driver = azuread.DriverName
					}
					return sql.Open(driver, params)
				}, nil
			},
		*/
		Version: func(ctx context.Context, db drivers.DB) (string, error) {
			var ver, level, edition string
			err := db.QueryRowContext(
				ctx,
				`SELECT SERVERPROPERTY('productversion'), SERVERPROPERTY ('productlevel'), SERVERPROPERTY ('edition')`,
			).Scan(&ver, &level, &edition)
			if err != nil {
				return "", err
			}
			return "Microsoft SQL Server " + ver + ", " + level + ", " + edition, nil
		},
		ChangePassword: f
    
func init() {
	drivers.Register("sqlserver", drivers.Driver{
		AllowMultilineComments:  true,
		RequirePreviousPassword: true,
		LexerName:               "tsql",
		/*
			// NOTE: this has been commented out, as it is not necessary. if
			// NOTE: the azuread.DriverName is changed from `azuresql`, then
			// NOTE: this func will be necessary as dburl will never import non
			// NOTE: stdlib package. as is, dburl.Open will handle the call
			// NOTE: to sql.Open and will pass the `azuresql` driver name
			Open: func(_ context.Context, u *dburl.URL, _, _ func() io.Writer) (func(string, string) (*sql.DB, error), error) {
				return func(_ string, params string) (*sql.DB, error) {
					driver := "sqlserver"
					switch {
					case u.Query().Has("fedauth"),
						strings.Contains(strings.ToLower(u.OriginalScheme), "azuresql"):
						driver = azuread.DriverName
					}
					return sql.Open(driver, params)
				}, nil
			},
		*/
		Version: func(ctx context.Context, db drivers.DB) (string, error) {
			var ver, level, edition string
			err := db.QueryRowContext(
				ctx,
				`SELECT SERVERPROPERTY('productversion'), SERVERPROPERTY ('productlevel'), SERVERPROPERTY ('edition')`,
			).Scan(&ver, &level, &edition)
			if err != nil {
				return "", err
			}
			return "Microsoft SQL Server " + ver + ", " + level + ", " + edition, nil
		},
		ChangePassword: func(db drivers.DB, user, newpw, oldpw string) error {
			_, err := db.Exec(`ALTER LOGIN ` + user + ` WITH password = '` + newpw + `' old_password = '` + oldpw + `'`)
			return err
		},
		ColumnTypes: func(col *sql.ColumnType) (interface{}, error) {
			switch col.DatabaseTypeName() {
			case "UNIQUEIDENTIFIER":
				if nullable, ok := col.Nullable(); ok && nullable {
					return new(NullUniqueIdentifier), nil
				}
				return new(mssql.UniqueIdentifier), nil
			}
			return new(interface{}), nil
		},
		Err: func(err error) (string, string) {
			if e, ok := err.(sqlserver.Error); ok {
				return strconv.Itoa(int(e.Number)), e.Message
			}
			msg := err.Error()
			if i := strings.LastIndex(msg, "sqlserver:"); i != -1 {
				msg = msg[i:]
			}
			return "", msg
		},
		IsPasswordErr: func(err error) bool {
			return strings.Contains(err.Error(), "Login failed for")
		},
		NewMetadataReader: NewReader,
		NewMetadataWriter: func(db drivers.DB, w io.Writer, opts ...metadata.ReaderOption) metadata.Writer {
			return metadata.NewDefaultWriter(NewReader(db, opts...))(db, w)
		},
		Copy: drivers.CopyWithInsert(placeholder),
	})
}