我正在嘗試為以下內(nèi)容編寫 Nhibernate ICriteria。SELECT *
FROM foo
WHERE
(fooKeyColumn1, fooKeyColumn2) IN (
SELECT barKeyColumn1, barKeyColumn2
FROM bar
WHERE <some conditions>)如果我需要檢查一列的 IN，那么我可以使用Subqueries.PropertyIn(propertyName,detachedCriteria);但如果我想檢查上面 sql 示例中給出的多個屬性的相同屬性，就會遇到麻煩。任何 NHibernate 專家可以指導(dǎo)我完成這個任務(wù)嗎？我想將此子查詢映射到使用 ICriteria 作為關(guān)鍵組件開發(fā)的現(xiàn)有模塊中。
1 回答
茅侃侃
TA貢獻1842條經(jīng)驗 獲得超21個贊
您需要自定義實現(xiàn)SubqueryExpression來實現(xiàn)它：
/// <summary>
/// A comparison between multiple properties in the outer query and the
/// result of a subquery
/// Note: DB support of row value constructor is required
/// </summary>
[Serializable]
public class MultiPropertiesSubqueryExpression : SubqueryExpression
{
private readonly string[] _propertyNames;
public MultiPropertiesSubqueryExpression(string[] propertyNames, string op, DetachedCriteria dc)
: base(op, null, dc)
{
_propertyNames = propertyNames;
}
protected override SqlString ToLeftSqlString(ICriteria criteria, ICriteriaQuery criteriaQuery)
{
return new SqlString("(", string.Join(", ", _propertyNames.Select(pn => criteriaQuery.GetColumns(criteria, pn)).SelectMany(x => x)), ")");
}
}
以及用法示例：
DetachedCriteria detachedCriteria = DetachedCriteria.For(typeof(Bar))
//.Add(...) //Add some conditions
.SetProjection(Projections.ProjectionList().Add(Property.ForName("Prop1")).Add(Property.ForName("Prop2")));
var result = session.CreateCriteria(typeof(Foo))
.Add(new MultiPropertiesSubqueryExpression(new[] {"Prop1", "Prop2"}, "in", detachedCriteria))
.List<Foo>();
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