type Join struct {
	Type       JoinType
	Table      Table
	ON         Where
	Using      []string
	Expression Expression
}

func JoinTable(names ...string) Table {
	return Table{
		Name: utils.JoinNestedRelationNames(names),
	}
}

func (join Join) Build(builder Builder) {
	if join.Expression != nil {
		join.Expression.Build(builder)
	} else {
		if join.Type != "" {
			builder.WriteString(string(join.Type))

    <description> This is the MavenProject instance for the parent of the current POM.
    </description>
  </expression>
  <expression>
    <syntax>project.file</syntax>
    <description> This is the File instance that refers to the location of the current POM on
      disk.
    </description>
  </expression>
  <expression>
    <syntax>project.artifacts</syntax>
    <configuration>
      <![CDATA[
<dependencies>
  ...

			},
			sql: "INNER JOIN `user` USING (`id`)",
		},
		{
			name: "Expression",
			join: clause.Join{
				// Invalid
				Type:  clause.LeftJoin,
				Table: clause.Table{Name: "user"},
				ON: clause.Where{
					Exprs: []clause.Expression{clause.Eq{clause.Column{Table: "user_info", Name: "user_id"}, clause.PrimaryColumn}},
				},
				// Valid
				Expression: clause.Join{
					Type:  clause.InnerJoin,

				Exprs: []clause.Expression{clause.Or(clause.Neq{Column: "name", Value: "jinzhu"}), clause.Eq{Column: clause.PrimaryColumn, Value: "1"}, clause.Gt{Column: "age", Value: 18}},
			}},
			"SELECT * FROM `users` WHERE `users`.`id` = ? OR `name` <> ? AND `age` > ?",
			[]interface{}{"1", "jinzhu", 18},
		},
		{
			[]clause.Interface{clause.Select{}, clause.From{}, clause.Where{

type Clause struct {
	Name                string // WHERE
	BeforeExpression    Expression
	AfterNameExpression Expression
	AfterExpression     Expression
	Expression          Expression
	Builder             ClauseBuilder
}

// Build build clause
func (c Clause) Build(builder Builder) {
	if c.Builder != nil {
		c.Builder(c, builder)
	} else if c.Expression != nil {
		if c.BeforeExpression != nil {
			c.BeforeExpression.Build(builder)

func (where Where) MergeClause(clause *Clause) {
	if w, ok := clause.Expression.(Where); ok {
		exprs := make([]Expression, len(w.Exprs)+len(where.Exprs))
		copy(exprs, w.Exprs)
		copy(exprs[len(w.Exprs):], where.Exprs)
		where.Exprs = exprs
	}

	clause.Expression = where
}

func And(exprs ...Expression) Expression {
	if len(exprs) == 0 {
		return nil
	}

	if len(exprs) == 1 {

      </codeSegments>
    </class>
    <class>
      <version>1.0.0</version>
      <name>Expression</name>
      <description>A plugin parameter expression supported by Maven</description>
      <fields>
        <field>
          <version>1.0.0</version>
          <name>syntax</name>
          <description>The syntax of the expression</description>
          <type>String</type>
          <required>true</required>
        </field>

     */
    @Override
    public Object getValue(String expression) {
        if (expression == null || expression.trim().isEmpty()) {
            return null;
        }

        try {
            return ReflectionValueExtractor.evaluate(expression, root, false);
        } catch (Exception e) {
            addFeedback("Failed to extract \'" + expression + "\' from: " + root, e);
        }

        return null;
    }

import org.codehaus.plexus.component.configurator.expression.ExpressionEvaluationException;
import org.codehaus.plexus.component.configurator.expression.TypeAwareExpressionEvaluator;

/**
 * Evaluator for plugin parameters expressions. Content surrounded by <code>${</code> and <code>}</code> is evaluated.
 * Recognized values are:
 * <table border="1">
 * <caption>Expression matrix</caption>

	Desc    bool
	Reorder bool
}

type OrderBy struct {
	Columns    []OrderByColumn
	Expression Expression
}

// Name where clause name
func (orderBy OrderBy) Name() string {
	return "ORDER BY"
}

// Build build where clause
func (orderBy OrderBy) Build(builder Builder) {
	if orderBy.Expression != nil {
		orderBy.Expression.Build(builder)
	} else {
		for idx, column := range orderBy.Columns {
			if idx > 0 {