"strings"

	"gorm.io/gorm/clause"
)

// reg match english letters and midline
var regEnLetterAndMidline = regexp.MustCompile(`^[\w-]+$`)

type CheckConstraint struct {
	Name       string
	Constraint string // length(phone) >= 10
	*Field
}

func (chk *CheckConstraint) GetName() string { return chk.Name }

func (chk *CheckConstraint) Build() (sql string, vars []interface{}) {

						clause.NamedExpr{"?", []interface{}{clause.Column{Name: "id"}}},
						clause.NamedExpr{"?", []interface{}{clause.Column{Name: "name"}}},
						clause.NamedExpr{"LENGTH(?)", []interface{}{clause.Column{Name: "mobile"}}},
					},
				},
			}, clause.From{}},
			"SELECT `id`, `name`, LENGTH(`mobile`) FROM `users`", nil,
		},
		{
			[]clause.Interface{clause.Select{
				Expression: clause.CommaExpression{
					Exprs: []clause.Expression{

					isSameType = true
					break
				}
			}

			if !isSameType {
				alterColumn = true
			}
		}
	}

	if !isSameType {
		// check size
		if length, ok := columnType.Length(); length != int64(field.Size) {
			if length > 0 && field.Size > 0 {
				alterColumn = true
			} else {
				// has size in data type and not equal

	expects := []User{
		{Name: "distinct", Age: 20},
		{Name: "distinct", Age: 18},
		{Name: "distinct-2", Age: 18},
		{Name: "distinct-3", Age: 18},
	}

	if len(results) != 4 {
		t.Fatalf("invalid results length found, expects: %v, got %v", len(expects), len(results))
	}

	for idx, expect := range expects {
		AssertObjEqual(t, results[idx], expect, "Name", "Age")
	}

	var count int64

	return ct.AutoIncrementValue.Bool, ct.AutoIncrementValue.Valid
}

// Length returns the column type length for variable length column types
func (ct ColumnType) Length() (length int64, ok bool) {
	if ct.LengthValue.Valid {
		return ct.LengthValue.Int64, true
	}
	return ct.SQLColumnType.Length()
}

// DecimalSize returns the scale and precision of a decimal type.

					t.Fatalf("column name type should be correct, name: %v, length: %v, expects: %v, column: %#v",
						columnType.Name(), columnType.DatabaseTypeName(), dataType, columnType)
				}
				if length, ok := columnType.Length(); !ok || length != 100 {
					t.Fatalf("column name length should be correct, name: %v, length: %v, expects: %v, column: %#v",
						columnType.Name(), length, 100, columnType)
				}
			case "age":

	// ErrInvalidValue invalid value
	ErrInvalidValue = errors.New("invalid value, should be pointer to struct or slice")
	// ErrInvalidValueOfLength invalid values do not match length
	ErrInvalidValueOfLength = errors.New("invalid association values, length doesn't match")
	// ErrPreloadNotAllowed preload is not allowed when count is used
	ErrPreloadNotAllowed = errors.New("preload is not allowed when count is used")

	Name() string
	DatabaseTypeName() string                 // varchar
	ColumnType() (columnType string, ok bool) // varchar(64)
	PrimaryKey() (isPrimaryKey bool, ok bool)
	AutoIncrement() (isAutoIncrement bool, ok bool)
	Length() (length int64, ok bool)
	DecimalSize() (precision int64, scale int64, ok bool)
	Nullable() (nullable bool, ok bool)
	Unique() (unique bool, ok bool)
	ScanType() reflect.Type
	Comment() (value string, ok bool)

							appendToElems(obj)
						}
					}
				case reflect.Struct:
					appendToElems(db.Statement.ReflectValue)
				}

				// optimize elems of reflect value length
				if elemLen := elems.Len(); elemLen > 0 {
					if v, ok := selectColumns[rel.Name+".*"]; !ok || v {
						saveAssociations(db, rel, distinctElems, selectColumns, restricted, nil)
					}

							AssertEqual(t, reflect.ValueOf(got).Index(i).Interface(), reflect.ValueOf(expect).Index(i).Interface())
						})
					}
				} else {
					name := reflect.ValueOf(got).Type().Elem().Name()
					t.Errorf("%v expects length: %v, got %v (expects: %+v, got %+v)", name, reflect.ValueOf(expect).Len(), reflect.ValueOf(got).Len(), expect, got)
				}
				return
			}
		}

		if reflect.ValueOf(got).Kind() == reflect.Struct {