column := "column-name"
	results := []struct {
		Expressions  []clause.Expression
		ExpectedVars []interface{}
		Result       string
	}{{
		Expressions: []clause.Expression{
			clause.Eq{Column: column, Value: "column-value"},
		},
		ExpectedVars: []interface{}{"column-value"},
		Result:       "`column-name` = ?",
	}, {
		Expressions: []clause.Expression{
			clause.Eq{Column: column, Value: nil},

	if !selectAST.Expression.All &&
		len(selectAST.Expression.Expressions) == 1 &&
		len(selectAST.Expression.Expressions[0].Expression.And) == 1 &&
		len(selectAST.Expression.Expressions[0].Expression.And[0].Condition) == 1 &&
		selectAST.Expression.Expressions[0].Expression.And[0].Condition[0].Operand != nil &&
		selectAST.Expression.Expressions[0].Expression.And[0].Condition[0].Operand.Operand.Left != nil &&

	strippedTableAlias string
	strippedPathExpr   []*JSONPathElement
}

// AliasedExpression is an expression that can be optionally named
type AliasedExpression struct {
	Expression *Expression `parser:"@@"`
	As         string      `parser:"[ \"AS\" @Ident | \"AS\" @LitString ]"`
}

// Grammar for Expression
//
// Expression          → AndCondition ("OR" AndCondition)*
// AndCondition        → Condition ("AND" Condition)*

}

func (s Select) MergeClause(clause *Clause) {
	if s.Expression != nil {
		if s.Distinct {
			if expr, ok := s.Expression.(Expr); ok {
				expr.SQL = "DISTINCT " + expr.SQL
				clause.Expression = expr
				return
			}
		}

		clause.Expression = s.Expression
	} else {
		clause.Expression = s
	}
}

// CommaExpression represents a group of expressions separated by commas.
type CommaExpression struct {

	if e.All {
		return qProp{isRowFunc: true}
	}

	for _, ex := range e.Expressions {
		result.combine(ex.analyze(s))
	}
	return
}

func (e *AliasedExpression) analyze(s *Select) qProp {
	return e.Expression.analyze(s)
}

func (e *Expression) analyze(s *Select) (result qProp) {
	for _, ac := range e.And {
		result.combine(ac.analyze(s))
	}
	return
}

	)

	// optimize match english letters and midline
	// The following code is basically called in for.
	// In order to avoid the performance problems caused by repeated compilation of regular expressions,
	// it only needs to be done once outside, so optimization is done here.
	if idx != -1 && regEnLetterAndMidline.MatchString(str[0:idx]) {
		name = str[0:idx]
	} else {

	if err != nil {
		t.Fatalf("parse alias sql error: %v", err)
	}
	if exp.selectAST.Expression.Expressions[2].As != "mytest" {
		t.Fatalf("parse alias sql error: %s not equal %s", exp.selectAST.Expression.Expressions[2].As, err)
	}

		cause:      err,
	}
}

func errInvalidExpressionType(err error) *s3Error {
	return &s3Error{
		code:       "InvalidExpressionType",
		message:    "The ExpressionType is invalid. Only SQL expressions are supported.",
		statusCode: 400,
		cause:      err,
	}
}

func errMissingRequiredParameter(err error) *s3Error {
	return &s3Error{
		code:       "MissingRequiredParameter",

		}
	}

	// Remove functions only used as expressions, so their respective
	// bridge functions are not generated.
	for name, used := range functions {
		if !used {
			delete(f.Name, name)
		}
	}
}

// rewriteName returns the expression used to rewrite a reference.
// If addPosition is true, add position info in the ident name.

		Description:    "Did not find the expected identifier for AT name in the SQL expression.",
		HTTPStatusCode: http.StatusBadRequest,
	},
	ErrParseAsteriskIsNotAloneInSelectList: {
		Code:           "ParseAsteriskIsNotAloneInSelectList",
		Description:    "Other expressions are not allowed in the SELECT list when '*' is used without dot notation in the SQL expression.",
		HTTPStatusCode: http.StatusBadRequest,
	},