use SQL standard CURRENT_TIMESTAMP instead of connection type specifi…

…c Now() method

connection.go

@@ -50,12 +50,6 @@ type Connection interface {
 	// column of the connection's database.
 	ValidateColumnName(name string) error
 
-	// Now returns the result of the SQL now()
-	// function for the current connection.
-	// Useful for getting the timestamp of a
-	// SQL transaction for use in Go code.
-	Now() (time.Time, error)
-
 	// Exec executes a query with optional args.
 	Exec(query string, args ...any) error
 

db/query.go

@@ -12,17 +12,20 @@ import (
 	"github.com/domonda/go-sqldb"
 )
 
-// Now returns the result of the SQL now()
-// function for the current connection.
+// CurrentTimestamp returns the SQL CURRENT_TIMESTAMP
+// for the connection added to the context
+// or else the default connection.
+//
+// Returns time.Now() in case of any error.
+//
 // Useful for getting the timestamp of a
 // SQL transaction for use in Go code.
-// Returns time.Now() in case of an error.
-func Now(ctx context.Context) time.Time {
-	now, err := Conn(ctx).Now()
+func CurrentTimestamp(ctx context.Context) time.Time {
+	t, err := QueryValue[time.Time](ctx, "SELECT CURRENT_TIMESTAMP")
 	if err != nil {
 		return time.Now()
 	}
-	return now
+	return t
 }
 
 // Exec executes a query with optional args.

db/utils.go

@@ -7,6 +7,7 @@ import (
 	"fmt"
 	"io"
 	"os"
+	"time"
 	"unicode/utf8"
 
 	"github.com/domonda/go-sqldb"
@@ -37,9 +38,10 @@ func DebugPrintConn(ctx context.Context, args ...any) {
 			args = append(args, "Isolation", optsStr)
 		}
 	}
-	now, err := Conn(ctx).Now()
+	var t time.Time
+	err := Conn(ctx).QueryRow("SELECT CURRENT_TIMESTAMP").Scan(&t)
 	if err == nil {
-		args = append(args, "NOW():", now)
+		args = append(args, "CURRENT_TIMESTAMP:", t)
 	} else {
 		args = append(args, "ERROR:", err)
 	}

errors.go

@@ -212,10 +212,6 @@ func (e connectionWithError) ValidateColumnName(name string) error {
 	return e.err
 }
 
-func (e connectionWithError) Now() (time.Time, error) {
-	return time.Time{}, e.err
-}
-
 func (e connectionWithError) Exec(query string, args ...any) error {
 	return e.err
 }

impl/connection.go

@@ -82,10 +82,6 @@ func (conn *connection) ValidateColumnName(name string) error {
 	return conn.validateColumnName(name)
 }
 
-func (conn *connection) Now() (time.Time, error) {
-	return Now(conn)
-}
-
 func (conn *connection) Exec(query string, args ...any) error {
 	_, err := conn.db.ExecContext(conn.ctx, query, args...)
 	return WrapNonNilErrorWithQuery(err, query, conn.argFmt, args)

impl/transaction.go

@@ -64,10 +64,6 @@ func (conn *transaction) ValidateColumnName(name string) error {
 	return conn.parent.validateColumnName(name)
 }
 
-func (conn *transaction) Now() (time.Time, error) {
-	return Now(conn)
-}
-
 func (conn *transaction) Exec(query string, args ...any) error {
 	_, err := conn.tx.Exec(query, args...)
 	return WrapNonNilErrorWithQuery(err, query, conn.parent.argFmt, args)

mockconn/connection.go

@@ -80,10 +80,6 @@ func (conn *connection) Ping(time.Duration) error {
 	return nil
 }
 
-func (conn *connection) Now() (time.Time, error) {
-	return time.Now(), nil
-}
-
 func (conn *connection) Exec(query string, args ...any) error {
 	if conn.queryWriter != nil {
 		fmt.Fprint(conn.queryWriter, query)

pqconn/connection.go

@@ -106,10 +106,6 @@ func (conn *connection) ValidateColumnName(name string) error {
 	return validateColumnName(name)
 }
 
-func (conn *connection) Now() (time.Time, error) {
-	return impl.Now(conn)
-}
-
 func (conn *connection) Exec(query string, args ...any) error {
 	impl.WrapArrayArgs(args)
 	_, err := conn.db.ExecContext(conn.ctx, query, args...)

pqconn/transaction.go

@@ -63,10 +63,6 @@ func (conn *transaction) ValidateColumnName(name string) error {
 	return validateColumnName(name)
 }
 
-func (conn *transaction) Now() (time.Time, error) {
-	return impl.Now(conn)
-}
-
 func (conn *transaction) Exec(query string, args ...any) error {
 	impl.WrapArrayArgs(args)
 	_, err := conn.tx.Exec(query, args...)