{"id":127,"date":"2008-05-01T17:32:53","date_gmt":"2008-05-01T17:32:53","guid":{"rendered":""},"modified":"2008-05-01T17:32:53","modified_gmt":"2008-05-01T17:32:53","slug":"127","status":"publish","type":"post","link":"https:\/\/www.poloo.org\/?p=127","title":{"rendered":"LINQ\u4f53\u9a8c(8)\u2014\u2014LINQ to SQL\u8bed\u53e5\u4e4bUnion All\/Union\/Intersect"},"content":{"rendered":"

LINQ\u4f53\u9a8c(8)——LINQ to SQL\u8bed\u53e5\u4e4bUnion All\/Union\/Intersect\u548cTop\/Bottom\u548cPaging\u548cSqlMethods<\/font><\/h1>\n

\u6211\u4eec\u7ee7\u7eed\u8bb2\u89e3LINQ to SQL\u8bed\u53e5\uff0c\u8fd9\u7bc7\u6211\u4eec\u6765\u8ba8\u8bbaUnion All\/Union\/Intersect\u64cd\u4f5c\u548cTop\/Bottom\u64cd\u4f5c\u548cPaging\u64cd\u4f5c\u548cSqlMethods\u64cd\u4f5c \u3002<\/p>\n

Union All\/Union\/Intersect\u64cd\u4f5c<\/font><\/h1>\n

\u9002\u7528\u573a\u666f\uff1a\u5bf9\u4e24\u4e2a\u96c6\u5408\u7684\u5904\u7406\uff0c\u4f8b\u5982\u8ffd\u52a0\u3001\u5408\u5e76\u3001\u53d6\u76f8\u540c\u9879\u3001\u76f8\u4ea4\u9879\u7b49\u7b49\u3002<\/p>\n

Concat\uff08\u8fde\u63a5\uff09<\/h1>\n

\u8bf4\u660e\uff1a\u8fde\u63a5\u4e0d\u540c\u7684\u96c6\u5408\uff0c\u4e0d\u4f1a\u81ea\u52a8\u8fc7\u6ee4\u76f8\u540c\u9879\uff1b\u5ef6\u8fdf\u3002<\/p>\n

1.\u7b80\u5355\u5f62\u5f0f\uff1a<\/h2>\n
var <\/span>q = (\r\nfrom <\/span>c in <\/span>db.Customers\r\nselect <\/span>c.Phone\r\n).Concat(\r\nfrom <\/span>c in <\/span>db.Customers\r\nselect <\/span>c.Fax\r\n).Concat(\r\nfrom <\/span>e in <\/span>db.Employees\r\nselect <\/span>e.HomePhone\r\n);<\/pre>\n
\u8bed\u53e5\u63cf\u8ff0\uff1a\u8fd4\u56de\u6240\u6709\u6d88\u8d39\u8005\u548c\u96c7\u5458\u7684\u7535\u8bdd\u548c\u4f20\u771f\u3002<\/p>\n
2.\u590d\u5408\u5f62\u5f0f\uff1a<\/h2>\n
var <\/span>q = (\r\nfrom <\/span>c in <\/span>db.Customers\r\nselect new\r\n<\/span>{\r\nName = c.CompanyName,\r\nc.Phone\r\n}\r\n).Concat(\r\nfrom <\/span>e in <\/span>db.Employees\r\nselect new\r\n<\/span>{\r\nName = e.FirstName + " " <\/span>+ e.LastName,\r\nPhone = e.HomePhone\r\n}\r\n);<\/pre>\n
\u8bed\u53e5\u63cf\u8ff0\uff1a\u8fd4\u56de\u6240\u6709\u6d88\u8d39\u8005\u548c\u96c7\u5458\u7684\u59d3\u540d\u548c\u7535\u8bdd\u3002<\/p>\n
Union\uff08\u5408\u5e76\uff09<\/h1>\n
\u8bf4\u660e\uff1a\u8fde\u63a5\u4e0d\u540c\u7684\u96c6\u5408\uff0c\u81ea\u52a8\u8fc7\u6ee4\u76f8\u540c\u9879\uff1b\u5ef6\u8fdf\u3002\u5373\u662f\u5c06\u4e24\u4e2a\u96c6\u5408\u8fdb\u884c\u5408\u5e76\u64cd\u4f5c\uff0c\u8fc7\u6ee4\u76f8\u540c\u7684\u9879\u3002<\/p>\n
var <\/span>q = (\r\nfrom <\/span>c in <\/span>db.Customers\r\nselect <\/span>c.Country\r\n).Union(\r\nfrom <\/span>e in <\/span>db.Employees\r\nselect <\/span>e.Country\r\n);<\/pre>\n
\u8bed\u53e5\u63cf\u8ff0\uff1a\u67e5\u8be2\u987e\u5ba2\u548c\u804c\u5458\u6240\u5728\u7684\u56fd\u5bb6\u3002<\/p>\n
Intersect\uff08\u76f8\u4ea4\uff09<\/h1>\n
\u8bf4\u660e\uff1a\u53d6\u76f8\u4ea4\u9879\uff1b\u5ef6\u8fdf\u3002\u5373\u662f\u83b7\u53d6\u4e0d\u540c\u96c6\u5408\u7684\u76f8\u540c\u9879\uff08\u4ea4\u96c6\uff09\u3002\u5373\u5148\u904d\u5386\u7b2c\u4e00\u4e2a\u96c6\u5408\uff0c\u627e\u51fa\u6240\u6709\u552f\u4e00\u7684\u5143\u7d20\uff0c\u7136\u540e\u904d\u5386\u7b2c\u4e8c\u4e2a\u96c6\u5408\uff0c\u5e76\u5c06\u6bcf\u4e2a\u5143\u7d20\u4e0e\u524d\u9762\u627e\u51fa\u7684\u5143\u7d20\u4f5c\u5bf9\u6bd4\uff0c\u8fd4\u56de\u6240\u6709\u5728\u4e24\u4e2a\u96c6\u5408\u5185\u90fd\u51fa\u73b0\u7684\u5143\u7d20\u3002<\/p>\n
var <\/span>q = (\r\nfrom <\/span>c in <\/span>db.Customers\r\nselect <\/span>c.Country\r\n).Intersect(\r\nfrom <\/span>e in <\/span>db.Employees\r\nselect <\/span>e.Country\r\n);<\/pre>\n
\u8bed\u53e5\u63cf\u8ff0\uff1a\u67e5\u8be2\u987e\u5ba2\u548c\u804c\u5458\u540c\u5728\u7684\u56fd\u5bb6\u3002<\/p>\n
Except\uff08\u4e0e\u975e\uff09<\/h1>\n
\u8bf4\u660e\uff1a\u6392\u9664\u76f8\u4ea4\u9879\uff1b\u5ef6\u8fdf\u3002\u5373\u662f\u4ece\u67d0\u96c6\u5408\u4e2d\u5220\u9664\u4e0e\u53e6\u4e00\u4e2a\u96c6\u5408\u4e2d\u76f8\u540c\u7684\u9879\u3002\u5148\u904d\u5386\u7b2c\u4e00\u4e2a\u96c6\u5408\uff0c\u627e\u51fa\u6240\u6709\u552f\u4e00\u7684\u5143\u7d20\uff0c\u7136\u540e\u518d\u904d\u5386\u7b2c\u4e8c\u4e2a\u96c6\u5408\uff0c\u8fd4\u56de\u7b2c\u4e8c\u4e2a\u96c6\u5408\u4e2d\u6240\u6709\u672a\u51fa\u73b0\u5728\u524d\u9762\u6240\u5f97\u5143\u7d20\u96c6\u5408\u4e2d\u7684\u5143\u7d20\u3002<\/p>\n
var <\/span>q = (\r\nfrom <\/span>c in <\/span>db.Customers\r\nselect <\/span>c.Country\r\n).Except(\r\nfrom <\/span>e in <\/span>db.Employees\r\nselect <\/span>e.Country\r\n);<\/pre>\n
\u8bed\u53e5\u63cf\u8ff0\uff1a\u67e5\u8be2\u987e\u5ba2\u548c\u804c\u5458\u4e0d\u540c\u7684\u56fd\u5bb6\u3002<\/p>\n
Top\/Bottom\u64cd\u4f5c<\/h1>\n
\u9002\u7528\u573a\u666f\uff1a\u9002\u91cf\u7684\u53d6\u51fa\u81ea\u5df1\u60f3\u8981\u7684\u6570\u636e\uff0c\u4e0d\u662f\u5168\u90e8\u53d6\u51fa\uff0c\u8fd9\u6837\u6027\u80fd\u6709\u6240\u52a0\u5f3a\u3002<\/p>\n
Take<\/h1>\n
\u8bf4\u660e\uff1a\u83b7\u53d6\u96c6\u5408\u7684\u524dn\u4e2a\u5143\u7d20\uff1b\u5ef6\u8fdf\u3002\u5373\u53ea\u8fd4\u56de\u9650\u5b9a\u6570\u91cf\u7684\u7ed3\u679c\u96c6\u3002<\/p>\n
var <\/span>q = (\r\nfrom <\/span>e in <\/span>db.Employees\r\norderby <\/span>e.HireDate\r\nselect <\/span>e)\r\n.Take(5);<\/pre>\n
\u8bed\u53e5\u63cf\u8ff0\uff1a\u67e5\u8be2\u51fa\u6700\u65e95\u4f4d\u96c7\u7528\u7684\u96c7\u5458\u3002<\/p>\n
Skip<\/h1>\n
\u8bf4\u660e\uff1a\u8df3\u8fc7\u96c6\u5408\u7684\u524dn\u4e2a\u5143\u7d20\uff1b\u5ef6\u8fdf\u3002\u5373\u6211\u4eec\u8df3\u8fc7\u7ed9\u5b9a\u7684\u6570\u76ee\u8fd4\u56de\u540e\u9762\u7684\u7ed3\u679c\u96c6\u3002<\/p>\n
var <\/span>q = (\r\nfrom <\/span>p in <\/span>db.Products\r\norderby <\/span>p.UnitPrice descending\r\nselect <\/span>p)\r\n.Skip(10);<\/pre>\n
\u8bed\u53e5\u63cf\u8ff0\uff1a\u67e5\u8be2\u51fa\u7b2c11\u4e2a\u6700\u8d35\u4ea7\u54c1\u540e\u9762\u7684\u6240\u6709\u4ea7\u54c1\u3002<\/p>\n
TakeWhile<\/h1>\n
\u8bf4\u660e\uff1a\u76f4\u5230\u67d0\u4e00\u6761\u4ef6\u6210\u7acb\u5c31\u505c\u6b62\u83b7\u53d6\uff1b\u5ef6\u8fdf\u3002\u5373\u7528\u5176\u6761\u4ef6\u53bb\u4f9d\u6b21\u5224\u65ad\u6e90\u5e8f\u5217\u4e2d\u7684\u5143\u7d20\uff0c\u8fd4\u56de\u7b26\u5408\u5224\u65ad\u6761\u4ef6\u7684\u5143\u7d20\uff0c\u8be5\u5224\u65ad\u64cd\u4f5c\u5c06\u5728\u8fd4\u56defalse\u6216\u6e90\u5e8f\u5217\u7684\u672b\u5c3e\u7ed3\u675f \u3002<\/p>\n
SkipWhile<\/h1>\n
\u8bf4\u660e\uff1a\u76f4\u5230\u67d0\u4e00\u6761\u4ef6\u6210\u7acb\u5c31\u505c\u6b62\u8df3\u8fc7\uff1b\u5ef6\u8fdf\u3002\u5373\u7528\u5176\u6761\u4ef6\u53bb\u5224\u65ad\u6e90\u5e8f\u5217\u4e2d\u7684\u5143\u7d20\u5e76\u4e14\u8df3\u8fc7\u7b2c\u4e00\u4e2a\u7b26\u5408\u5224\u65ad\u6761\u4ef6\u7684\u5143\u7d20\uff0c\u4e00\u65e6\u5224\u65ad\u8fd4\u56defalse\uff0c\u63a5\u4e0b\u6765\u5c06\u4e0d\u518d\u8fdb\u884c\u5224\u65ad\u5e76\u8fd4\u56de\u5269\u4e0b\u7684\u6240\u6709\u5143\u7d20\u3002<\/p>\n
Paging\uff08\u5206\u9875\uff09\u64cd\u4f5c<\/h1>\n
\u9002\u7528\u573a\u666f\uff1a\u7ed3\u5408Skip\u548cTake\u5c31\u53ef\u5b9e\u73b0\u5bf9\u6570\u636e\u5206\u9875\u64cd\u4f5c\u3002<\/p>\n
var <\/span>q = (\r\nfrom <\/span>c in <\/span>db.Customers\r\norderby <\/span>c.ContactName\r\nselect <\/span>c)\r\n.Skip(50)\r\n.Take(10);<\/pre>\n
\u8bed\u53e5\u63cf\u8ff0\uff1a\u8df3\u8fc7\u524d50\u6761\u8bb0\u5f55\uff0c\u53d6\u51fa\u63a5\u4e0b\u6765\u768410\u6761\u8bb0\u5f55\uff0c\u5f62\u6210\u4e58\u79ef\u8868\u5728\u7b2c6\u9875\u663e\u793a\u3002<\/p>\n
var <\/span>q = (\r\nfrom <\/span>p in <\/span>db.Products\r\nwhere <\/span>p.ProductID > 50\r\norderby <\/span>p.ProductID\r\nselect <\/span>p)\r\n.Take(10);<\/pre>\n
SqlMethods\u64cd\u4f5c<\/h1>\n
\u5728LINQ to SQL\u8bed\u53e5\u4e2d\uff0c\u4e3a\u6211\u4eec\u63d0\u4f9b\u4e86SqlMethods\u64cd\u4f5c\uff0c\u8fdb\u4e00\u6b65\u4e3a\u6211\u4eec\u63d0\u4f9b\u4e86\u65b9\u4fbf\uff0c\u4f8b\u5982Like\u65b9\u6cd5\u7528\u4e8e\u81ea\u5b9a\u4e49\u901a\u914d\u8868\u8fbe\u5f0f\uff0cEquals\u7528\u4e8e\u76f8\u6bd4\u8f83\u662f\u5426\u76f8\u7b49\u3002<\/p>\n
Like<\/h1>\n
\u81ea\u5b9a\u4e49\u7684\u901a\u914d\u8868\u8fbe\u5f0f\u3002%\u8868\u793a\u96f6\u957f\u5ea6\u6216\u4efb\u610f\u957f\u5ea6\u7684\u5b57\u7b26\u4e32\uff1b_\u8868\u793a\u4e00\u4e2a\u5b57\u7b26\uff1b[]\u8868\u793a\u5728\u67d0\u8303\u56f4\u533a\u95f4\u7684\u4e00\u4e2a\u5b57\u7b26\uff1b[^]\u8868\u793a\u4e0d\u5728\u67d0\u8303\u56f4\u533a\u95f4\u7684\u4e00\u4e2a\u5b57\u7b26\u3002\u6bd4\u5982\u67e5\u8be2\u6d88\u8d39\u8005ID\u4ee5“C”\u5f00\u5934\u7684\u6d88\u8d39\u8005\u3002 <\/p>\n
var <\/span>q = from <\/span>c in <\/span>db.Customers\r\nwhere <\/span>SqlMethods<\/span>.Like(c.CustomerID, "C%"<\/span>)\r\nselect <\/span>c;<\/pre>\n
\u6bd4\u5982\u67e5\u8be2\u6d88\u8d39\u8005ID\u6ca1\u6709<\/strong>“AXOXT”\u5f62\u5f0f\u7684\u6d88\u8d39\u8005\uff1a<\/p>\n
var <\/span>q = from <\/span>c in <\/span>db.Customers\r\nwhere <\/span>!SqlMethods<\/span>.Like(c.CustomerID, "A_O_T"<\/span>)\r\nselect <\/span>c;<\/pre>\n
DateDiffDay<\/h1>\n
\u8bf4\u660e\uff1a\u5728\u4e24\u4e2a\u53d8\u91cf\u4e4b\u95f4\u6bd4\u8f83\u3002\u5206\u522b\u6709\uff1aDateDiffDay\u3001DateDiffHour\u3001DateDiffMillisecond\u3001DateDiffMinute\u3001DateDiffMonth\u3001DateDiffSecond\u3001DateDiffYear <\/p>\n
var <\/span>q = from <\/span>o in <\/span>db.Orders\r\nwhere <\/span>SqlMethods\r\n<\/span>.DateDiffDay(o.OrderDate, o.ShippedDate) < 10\r\nselect <\/span>o;<\/pre>\n
\u8bed\u53e5\u63cf\u8ff0\uff1a\u67e5\u8be2\u6240\u670910\u5929\u4e4b\u5185\u7684\u8ba2\u5355\u3002<\/p>\n
Compiled Query\u64cd\u4f5c<\/h1>\n
\u8bf4\u660e\uff1a\u5728\u4e4b\u524d\u6211\u4eec\u6ca1\u6709\u597d\u7684\u65b9\u6cd5\u5bf9\u5199\u51fa\u7684SQL\u8bed\u53e5\u8fdb\u884c\u7f16\u8f91\u91cd\u65b0\u67e5\u8be2\uff0c\u73b0\u5728\u6211\u4eec\u53ef\u4ee5\u8fd9\u6837\u505a\uff0c\u770b\u4e0b\u9762\u4e00\u4e2a\u4f8b\u5b50\uff1a<\/p>\n
\/\/1.\u521b\u5efacompiled query\r\n<\/span>NorthwindDataContext <\/span>db = new <\/span>NorthwindDataContext<\/span>();\r\nvar <\/span>fn = CompiledQuery<\/span>.Compile(\r\n(NorthwindDataContext <\/span>db2, string <\/span>city) =>\r\nfrom <\/span>c in <\/span>db2.Customers\r\nwhere <\/span>c.City == city\r\nselect <\/span>c);\r\n\/\/2.\u67e5\u8be2\u57ce\u5e02\u4e3aLondon\u7684\u6d88\u8d39\u8005,\u7528LonCusts\u96c6\u5408\u8868\u793a\uff0c\u8fd9\u65f6\u53ef\u4ee5\u7528\u6570\u636e\u63a7\u4ef6\u7ed1\u5b9a\r\n<\/span>var <\/span>LonCusts = fn(db, "London"<\/span>);\r\n\/\/3.\u67e5\u8be2\u57ce\u5e02\u4e3aSeattle\u7684\u6d88\u8d39\u8005\r\n<\/span>var <\/span>SeaCusts = fn(db, "Seattle"<\/span>);<\/pre>\n","protected":false},"excerpt":{"rendered":"
LINQ\u4f53\u9a8c(8)——LINQ to SQL...<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[13],"tags":[],"class_list":["post-127","post","type-post","status-publish","format-standard","hentry","category-NET"],"_links":{"self":[{"href":"https:\/\/www.poloo.org\/index.php?rest_route=\/wp\/v2\/posts\/127","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.poloo.org\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.poloo.org\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.poloo.org\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.poloo.org\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=127"}],"version-history":[{"count":0,"href":"https:\/\/www.poloo.org\/index.php?rest_route=\/wp\/v2\/posts\/127\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.poloo.org\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=127"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.poloo.org\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=127"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.poloo.org\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=127"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}