} else {
		name := v.Name()
		c := stmt.Clauses[name]
		c.Name = name
		v.MergeClause(&c)
		stmt.Clauses[name] = c
	}
}

// AddClauseIfNotExists add clause if not exists
func (stmt *Statement) AddClauseIfNotExists(v clause.Interface) {
	if c, ok := stmt.Clauses[v.Name()]; !ok || c.Expression == nil {
		stmt.AddClause(v)
	}
}

// BuildCondition build condition