LINQ to Entities ʵÏÖsql ¹Ø¼ü×Ö"In"·½Ê½×ܽá
ÔÚLINQ to EntitiesÖÐûÓа취ÔÙÏñ LINQ to SQL ÖÐÒ»ÑùʹÓà Contains µÄ·½·¨À´ÊµÏÖsql "in" ¹Ø¼ü×Ö
ÏÂÃæ´úÂëÔÚ LINQ to SQL ÖпÉÐÐ ÔÚLINQ to EntitiesÈ´ÎÞ·¨ÔËÐУº
var s = db.Account.Select(c => c.ID);
var ret =(from t in db.Profile
where s.Contains(t.ID)
select t).ToList();
Ìæ´ú·½·¨1:ʹÓ÷½·¨Any
var ids=db.Account.Select(c => c.ID);
var ret = (from t in db.Profile where ids.Any(c=>c==t.UserID) select t).ToList();
ʹÓ÷½·¨AnyÌæ»»·¨¸ãÁ˺þö¼Ã»·¨ÊµÏÖÖ±½Ó¶ÔÊý×éAny£¬ÏÂÁдúÂëÈÔÎÞ·¨Ö´ÐУº
int[] ids = new int[]{10101,10005,10007};
var ret = (from t in db.Profile where ids.Any(c=>c==t.UserID) select t).ToList();
ÓÚÊǼÌÐøGoolgeѰÕÒµÚ¶þÖÖ·½·¨£¬ÔÚMSDNÂÛ̳ÉÏÕÒÒ»¸ö¹¹ÔìLambdaÓï¾äµÄ·½·¨
Ìæ´ú·½·¨2:¹¹ÔìLambdaÓï¾ä
private static Expression<Func<TElement, bool>> BuildWhereInExpression<TElement, TValue>(Expression<Func<TElement, TValue>> propertySelector, IEnumerable<TValue> values)
{
ParameterExpression p = propertySelector.Parameters.Single();
if (!values.Any())
return e => false;
var equals = values.Select(value => (Expression)Expression.Equal(propertySelector.Body, Expression.Constant(value, typeof(TValue))));
var body&
Ïà¹ØÎĵµ£º
·½·¨Ò»
µÚÒ»²½£ºµÇÈësql/plus Ö´ÐÐÃüÁÎÞÏȺó˳Ðò£©
set time on; (˵Ã÷£º´ò¿ªÊ±¼äÏÔʾ£©
set autotrace on; (˵Ã÷£º´ò¿ª×Ô¶¯·ÖÎöͳ¼Æ£¬²¢ÏÔʾSQLÓï¾äµÄÔËÐнá¹û£©
set autotrace traceonly; (˵à ......
1.·ÖÎöϵͳÈÕÖ¾£¬Ò»ÐÐÒ»Ðп´×ÅʵÔÚÀÛÈË£¬ºÜ¶àÎÞ¹ØÈÕÖ¾£¬ÄܹýÂËϾͺÃÁË¡£Îı¾¹¤¾ß¹¦ÄÜʵÔÚÓÐÏÞ£¬ÓÚÊǺõ£¬½«windowsϵͳÈÕÖ¾µ¼Èësql serverÖУ¬Ö±½ÓsqlÖ®……¡£ÊµÑéÁ˼¸°Ñ£¬×îºÃµÄÊÇ£¬Ö±½Ó½«ÏµÍ³ÈÕÖ¾µ¼³öΪÎı¾µÄ£¬Ö±½Ótab·Ö¸îµÄ£¬µ¼ÈësqlµÄʱºò£º
н¨Êý¾Ý¿â->µ¼ÈëÊý¾Ý->ÏÂÒ»²½->Êý¾ÝÔ´Ñ¡ÔñÎı¾Îļþ- ......
Microsoft SQL Server2005¼¼ÊõÄÚÄ»:T-SQL³ÌÐòÉè¼Æ
http://www.amazon.cn/mn/detailApp/ref=sr_1_25?_encoding=UTF8&s=books&qid=1261538877&asin=B0011C2568&sr=8-25
Microsoft SQL Server 2005¼¼ÊõÄÚÄ»£º²éѯ¡¢µ÷ÕûºÍÓÅ»¯
http://www.amazon.cn/mn/detailApp/ref=sr_1_4?_encoding=UTF8&s=books&am ......
ÔÚSQLÓÅ»¯¹ý³ÌÖг£¼ûOracle HINTµÄÓ÷¨£º
1. /*+ALL_ROWS*/
±íÃ÷¶ÔÓï¾ä¿éÑ¡Ôñ»ùÓÚ¿ªÏúµÄÓÅ»¯·½·¨,²¢»ñµÃ×î¼ÑÍÌÍÂÁ¿,ʹ×ÊÔ´ÏûºÄ×îС»¯.
ÀýÈç:
SELECT /*+ALL+_ROWS*/ EMP_NO,EMP_NAM,DAT_IN from BSEMPMS WHERE EMP_NO='SCOTT';
2. /*+FIRST_ROW ......
±¾ÎÄÖ÷Òª½²ÊöÈý¸öÄÚÈÝ£º
1.ÈçºÎ´´½¨hierarychyidµÄ±í£¬²åÈëÊý¾Ý¼°»ù±¾µÝ¹é²éѯ¡£
2.½éÉÜhierarchyidµÄ10ÖÖרÓк¯Êý¡£
3.½éÉÜhierarchyidÌØÓеÄÉî¶ÈÓÅÏÈË÷Òý(Depth-First Indexing)ºÍ¹ã¶ÈÓÅÏÈË÷Òý(Breadth-First Indexing)
ÔÚÉÏÒ»½ÚÖÐ
http://blog.csdn.net/tjvictor/archive/2009/07/30/4395677.aspx
ÎÒÃÇÒѾÑÝ ......