我可以在運行時在Ormlite中構建自定義查詢嗎？

Question

我可以在運行時在ormlite中構建自定義查詢嗎？ 例如

public class SearchCriteria 
{ 
    public string FieldName { get; set; } 
    public MatchType MatchType { get; set; } 
    public object value1 { get; set; } 
    public object value2 { get; set; } 
} 
public enum MatchType { StartsWith, Contains, Between, GreaterThan } // ... etc. 
public class OrderCriteria 
{ 
    public string FieldName { get; set; } 
    public OrderDirection OrderDirection { get; set; } 
} 
public enum OrderDirection { Ascending, Descending } 

，然後我會打電話與

SearchCriteria[] sCrit = new SearchCriteria[2]; 
sCriteria[0] = new SearchCriteria{ FieldName = "Description", MatchType = MatchType.Contains, value1 = "vip" } 
sCriteria[1] = new SearchCriteria{ FieldName = "Description", MatchType = MatchType.Contains, value1 = "client" } 
OrderCriteria[] oCrit = new OrderCriteria[] { new OrderCriteria{ FieldName = "Description", OrderDirection = OrderDirection.Ascending} }; 
repo.GetItemsList(sCriteria, oCrit); 

庫，並留下實際LINQ創作是庫的責任。

如果可能，這會影響ormlite的性能嗎？

Answer 1

事實證明，選擇需要的SqlExpression作爲參數。 和SqlExpression內部，可以使用Sql語法構建查詢。

例如：

SqlExpression<T> expression = new MySqlExpression<T>(); 
       expression.WhereExpression = (whereExp.Length > 0 ? "WHERE " + whereExp : ""); 
       expression.OrderByExpression = (orderExp.Length > 0 ? "ORDER BY " + orderExp : ""); 
       expression = expression.Limit(skip: _pageIndex * _pageSize, rows: _pageSize);