public SqlFromQuery ToOutQuery(params SqlSelectItem[] selectItem)
{
if (selectItem == null || selectItem.Length <= 0)
{
throw new ArgumentException("must select some one");
}
foreach (var item in selectItem)
{
if (item.Target.Expression.Type == ExpressionType.SelectItemExpression)
{
SqlSelectItemExpression si = (SqlSelectItemExpression)item.Target.Expression;
if (si.Owner == this)
{
SqlSelectItemExpression tar = new SqlSelectItemExpression(si.Expression, item.Target.AliasName);
tar.Owner = this;
Selects.Add(item.Target.AliasName, tar);
}
else
{
Selects.Add(item.Target.AliasName, item.Target);
}
}
else
{
Selects.Add(item.Target.AliasName, item.Target);
}
}
return(new SqlFromQuery(this));
}
private void BuildSelectItem(SqlSelectItemExpression item, BuildQueryContext ctx)
{
//判断item.Expression是否是子Select项,是则表示外部查询（FromQuery）引用的Select项
if (item.Expression.Type == ExpressionType.SelectItemExpression)
{
SqlSelectItemExpression si = (SqlSelectItemExpression)item.Expression;
//判断当前查询是否等于Select项的所有者，否则表示Select项的所有者的外部查询引用该Select项
if (ReferenceEquals(ctx.CurrentQuery, item.Owner))
{
ctx.AppendFormat("{0}.\"{1}\"", ctx.GetQueryAliasName(si.Owner), si.AliasName);
}
else
{
ctx.AppendFormat("{0}.\"{1}\"", ctx.GetQueryAliasName(item.Owner), si.AliasName);
}
//处理选择项别名
if (ctx.CurrentQueryInfo.BuildStep == BuildQueryStep.BuildSelect)//&& !ctx.IsBuildCTESelectItem)
{
if (item.AliasName != si.AliasName)
{
ctx.AppendFormat(" \"{0}\"", item.AliasName);
}
}
}
else //----上面为FromQuery的Select项，下面为Query或SubQuery的Select项----
{
//判断当前查询是否等于Select项的所有者，否则表示Select项的所有者的外部查询引用该Select项
if (ReferenceEquals(ctx.CurrentQuery, item.Owner))
{
BuildExpression(item.Expression, ctx);
}
else
{
ctx.AppendFormat("{0}.\"{1}\"", ctx.GetQueryAliasName(item.Owner), item.AliasName);
}
//处理选择项别名
if (ctx.CurrentQueryInfo.BuildStep == BuildQueryStep.BuildSelect)//&& !ctx.IsBuildCTESelectItem)
{
MemberExpression memberExp = item.Expression as MemberExpression;
if (Expression.IsNull(memberExp)
/*|| memberExp.Type == ExpressionType.AggregationRefFieldExpression*/ //注意：聚合引用字段必须用别名
|| memberExp.Name != item.AliasName)
{
ctx.AppendFormat(" \"{0}\"", item.AliasName);
}
}
}
}
public SqlSelectItem(Expression val, string aliasName)
{
Target = new SqlSelectItemExpression(val, aliasName);
}
public SqlSelectItem(Expression val)
{
//Todo: 是否判断val是否已是QuerySelect类型
Target = new SqlSelectItemExpression(val);
}
public void AddSelectItem(SqlSelectItemExpression item)
{
item.Owner = this;
Selects.Add(item.AliasName, item);
}