private FromSection <T> Join <TJoin>(TableRelation <TJoin> relation, string aliasName, WhereClip onWhere, JoinType joinType)
where TJoin : Entity
{
//将TableRelation的对象添加到当前节
this.entities.AddRange(relation.GetFromSection().TableEntities);
TJoin entity = CoreHelper.CreateInstance <TJoin>();
var table = entity.GetTable().As(aliasName);
if ((IField)query.PagingField == null)
{
//标识列和主键优先,包含ID的列被抛弃
query.SetPagingField(entity.PagingField);
}
string tableName = entity.GetTable().Name;
if (aliasName != null)
{
tableName = aliasName;
}
//处理tableRelation关系
string joinString = "(" + relation.GetFromSection().Query.QueryString + ") " + tableName;
this.query.Parameters = relation.GetFromSection().Query.Parameters;
string strJoin = string.Empty;
if (onWhere != null)
{
strJoin = " ON " + onWhere.ToString();
}
//获取关联方式
string join = GetJoinEnumString(joinType);
if (this.relation != null)
{
this.tableName = " __[[ " + this.tableName;
this.relation += " ]]__ ";
}
this.relation += join + joinString + strJoin;
return(this);
}
/// <summary>
/// 返回一个Query节
/// </summary>
/// <typeparam name="T"></typeparam>
/// <returns></returns>
public QuerySection <T> From <T>(TableRelation <T> relation)
where T : Entity
{
//重新实例化一个Query
var query = new QuerySection <T>(relation.GetFromSection(), dbProvider, this);
//处理前n条
if (relation.GetTopSize() > 0)
{
query = query.GetTop(relation.GetTopSize());
}
return(query);
}