if err != nil {
		t.Fatalf("failed to connect database, got error %v", err)
	}

	dialectors := map[string]bool{"sqlite": true, "postgres": true, "gaussdb": true, "mysql": true, "sqlserver": true}
	if supported, found := dialectors[db.Dialector.Name()]; !(found && supported) {
		return
	}

	DB.Migrator().DropTable(&City{})

	if err = db.AutoMigrate(&City{}); err != nil {

	if err == nil {
		t.Fatalf("should returns error but got nil")
	}
}

func TestReturningWithNullToZeroValues(t *testing.T) {
	dialect := DB.Dialector.Name()
	switch dialect {
	case "mysql", "sqlserver":
		// these dialects do not support the "returning" clause
		return
	default:
		// This user struct will leverage the existing users table, but override
		// the Name field to default to null.

	sql := DB.Dialector.Explain(stmt.SQL.String(), stmt.Vars...)
	if !regexp.MustCompile(`.*age.*=8,`).MatchString(sql) {
		t.Errorf("Failed to generate sql, got %v", sql)
	}

	stmt = dryRunDB.Model(&user).Where("id = ?", 1).Updates(map[string]interface{}{"age": ageUint64(10241024)}).Statement
	sql = DB.Dialector.Explain(stmt.SQL.String(), stmt.Vars...)

package gorm

import (
	"context"
	"database/sql"

	"gorm.io/gorm/clause"
	"gorm.io/gorm/schema"
)

// Dialector GORM database dialector
type Dialector interface {
	Name() string
	Initialize(*DB) error
	Migrator(db *DB) Migrator
	DataTypeOf(*schema.Field) string
	DefaultValueOf(*schema.Field) clause.Expression
	BindVarTo(writer clause.Writer, stmt *Statement, v interface{})
	QuoteTo(clause.Writer, string)

	. "gorm.io/gorm/utils/tests"
)

func TestGaussDBReturningIDWhichHasStringType(t *testing.T) {
	t.Skipf("This test case skipped, because of gaussdb not support pgcrypto extension and gen_random_uuid() function")
	if DB.Dialector.Name() != "gaussdb" {
		t.Skip()
	}

	type Yasuo struct {
		// TODO: function gen_random_uuid() does not exist
		ID        string `gorm:"default:gen_random_uuid()"`
		Name      string

	PropagateUnscoped bool

	// ClauseBuilders clause builder
	ClauseBuilders map[string]clause.ClauseBuilder
	// ConnPool db conn pool
	ConnPool ConnPool
	// Dialector database dialector
	Dialector
	// Plugins registered plugins
	Plugins map[string]Plugin

	callbacks  *callbacks
	cacheStore *sync.Map
}

// Apply update config to new config
func (c *Config) Apply(config *Config) error {

	"time"

	"github.com/google/uuid"
	"github.com/lib/pq"
	"gorm.io/gorm"
	"gorm.io/gorm/clause"
	. "gorm.io/gorm/utils/tests"
)

func TestPostgresReturningIDWhichHasStringType(t *testing.T) {
	if DB.Dialector.Name() != "postgres" {
		t.Skip()
	}

	type Yasuo struct {
		ID        string `gorm:"default:gen_random_uuid()"`
		Name      string
		CreatedAt time.Time `gorm:"type:TIMESTAMP WITHOUT TIME ZONE"`

		}
	}
}

// only sqlite, postgres, gaussdb, sqlserver support returning
func TestSoftDeleteReturning(t *testing.T) {
	if DB.Dialector.Name() != "sqlite" && DB.Dialector.Name() != "postgres" && DB.Dialector.Name() != "gaussdb" && DB.Dialector.Name() != "sqlserver" {
		return
	}

	users := []*User{
		GetUser("delete-returning-1", Config{}),
		GetUser("delete-returning-2", Config{}),

			t.Fatalf("Failed to find index for many2many for %v %v", indexes[0], indexes[1])
		}
	}
}

func TestAutoMigrateInt8PGAndGaussDB(t *testing.T) {
	if DB.Dialector.Name() != "postgres" && DB.Dialector.Name() != "gaussdb" {
		return
	}

	type Smallint int8

	type MigrateInt struct {
		Int8 Smallint
	}

	tracer := Tracer{
		Logger: DB.Config.Logger,

	if name := DB.Dialector.Name(); name == "sqlite" || name == "sqlserver" {
		t.Skip("skip sqlite, sqlserver due to it doesn't support multiple primary keys with auto increment")
	}

	if name := DB.Dialector.Name(); name == "postgres" {
		t.Skip("skip postgres due to it only allow unique constraint matching given keys")
	}
	if name := DB.Dialector.Name(); name == "gaussdb" {