asp.net ef5 left join 的实现
最近在网上查找了很多的ef5实现left join的方法,很遗憾没有找到满意的结果,经过自己的研究终于发现了点眉目,所以分享一下
EF5: var x = ef.SYS_MODULE.GroupJoin(ef.SYS_ROLEMODULES, m => m.MKID, n => n.MKID, (w, c) => new { A = c, v = w });
说明:上面是用表SYS_MODULE left join 表 SYS_ROLEMODULES 用表SYS_MODULE.MKID 和 SYS_ROLEMODULES.MKID 关联
查询的结果放到标红的位置;但不知道为什么会自动产生C1,C2
x.ToString()的结果是:
SELECT "Project1"."MKID" AS "MKID",
"Project1"."C1" AS "C1",
"Project1"."MKMC" AS "MKMC",
"Project1"."C2" AS "C2",
"Project1"."JSID" AS "JSID",
"Project1"."MKID1" AS "MKID1"
FROM (SELECT "Extent1"."MKID" AS "MKID",
"Extent1"."MKMC" AS "MKMC",
1 AS "C1",
"Extent2"."JSID" AS "JSID",
"Extent2"."MKID" AS "MKID1",
CASE
WHEN ("Extent2"."JSID" IS NULL) THEN
NULL
ELSE
1
END AS "C2"
FROM "A1"."SYS_MODULE" "Extent1"
LEFT OUTER JOIN "A1"."SYS_ROLEMODULES" "Extent2"
ON ("Extent1"."MKID" = "Extent2"."MKID")
AND (‘1‘ = "Extent2"."MKID")) "Project1"
ORDER BY "Project1"."MKID" ASC, "Project1"."C2" ASC
x.ToList()的结果是标红位置的集合;
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