outer-join

How to do a full outer join in Linq?

由 流过昼夜 提交于 2019-11-27 12:20:31
I've inherited a database that wasn't designed exactly optimally, and I need to manipulate some data. Let me give a more common analogy of the kind of thing I have to do: Let's say we have a Student table, a StudentClass table keeping record of all the classes he attended, and a StudentTeacher table that stores all the teachers who taught this student. Yes, I know it's a dumb design and it would make more sense to store the teacher on the Class table - but that's what we're working with. I now want to clean up the data, and I want to find all the places where a student has a teacher but no

Conditions in LEFT JOIN (OUTER JOIN) vs INNER JOIN

由 ＊爱你＆永不变心＊ 提交于 2019-11-27 07:37:43
问题 SELECT A.COL1, B.COL1,C.COL1 FROM TABLEA A LEFT JOIN TABLEB B ON A.COL1 = B.COL1 LEFT JOIN TABLEC C ON ( C.COL3 IS NOT NULL AND ( C.COL2 = 664 AND A.COL1 = C.COL1 ) ) In regards to technicalities of SQL, what does the condition written in parentheses after LEFT JOIN TABLE C ON mean? Why are those necessary? 回答1: An inner join (JOIN or INNER JOIN, CROSS JOIN or comma) first does a CROSS JOIN. (Ie returns all rows that can be made by appending a row from its left table and a row from its right

Difference between RIGHT & LEFT JOIN vs RIGHT & LEFT OUTER JOIN in SQL [duplicate]

由 久未见 提交于 2019-11-27 02:27:36
This question already has an answer here: LEFT JOIN vs. LEFT OUTER JOIN in SQL Server 12 answers What is the difference in results between: RIGHT JOIN and RIGHT OUTER JOIN LEFT JOIN and LEFT OUTER JOIN ? Can you please explain it through some examples? Pranay Rana There is no difference between RIGHT JOIN and RIGHT OUTER JOIN . Both are the same. That is, LEFT JOIN and LEFT OUTER JOIN both are the same. Visual Representation of SQL Joins Here's a very nice Visual Explanation of joins generally by our very own Jeff Atwood. A right outer join is the same as a right join, and left join and left

How do I convert a “legacy” left outer join statement in Oracle?

由 百般思念 提交于 2019-11-26 22:26:23
问题 I have two tables (A and G) in an Oracle database that can be joined together based off an account number. The one caveat to this is that one of the tables (G) has about 80 fewer records than the other. When I query the two tables together, I need to get all of the rows, so that we see NULL data in the columns for the missing 80 rows. I currently have an Oracle statement that performs a left outer join query using the following "legacy" syntax: SELECT A.AccountNo, A.ParcelNo, A.LocalNo, A

Difference between RIGHT & LEFT JOIN vs RIGHT & LEFT OUTER JOIN in SQL [duplicate]

由 南楼画角 提交于 2019-11-26 22:14:14
问题 This question already has an answer here: LEFT JOIN vs. LEFT OUTER JOIN in SQL Server 12 answers What is the difference in results between: RIGHT JOIN and RIGHT OUTER JOIN LEFT JOIN and LEFT OUTER JOIN ? Can you please explain it through some examples? 回答1: There is no difference between RIGHT JOIN and RIGHT OUTER JOIN . Both are the same. That is, LEFT JOIN and LEFT OUTER JOIN both are the same. Visual Representation of SQL Joins 回答2: Here's a very nice Visual Explanation of joins generally

data.table inner/outer join with NA in join column of type double bug?

由 空扰寡人 提交于 2019-11-26 20:42:18
问题 Following this wikipedia article SQL join I wanted to have a clear view on how we could have joins with data.table. In the process we might have uncovered a bug when joining with NAs. Taking the wiki example: R) X = data.table(name=c("Raf","Jon","Ste","Rob","Smi","Joh"),depID=c(31,33,33,34,34,NA),key="depID") R) Y = data.table(depID=c(31,33,34,35),depName=c("Sal","Eng","Cle","Mar"),key="depID") R) X name depID 1: Joh NA 2: Raf 31 3: Jon 33 4: Ste 33 5: Rob 34 6: Smi 34 R) Y depID depName 1:

How to generalize outer to n dimensions?

由 给你一囗甜甜゛ 提交于 2019-11-26 16:39:30
问题 The standard R expression outer(X, Y, f) evaluates to a matrix whose (i, j)-th entry has the value f(X[i], Y[j]) . I would like to implement the function multi.outer , an n-dimensional generalization of outer : multi.outer(f, X_1, ..., X_n) , where f is some n-ary function, would produce a (length(X_1) * ... * length(X_n)) array whose (i_1,...,i_n)-th entry has the value f(X_1[i_1], ..., X_n[i_n]) for all valid index sets (i_1,...,i_n). Clearly, for each i in {1, ..., n}, all the elements of

How to do a full outer join in Linq?

由 给你一囗甜甜゛ 提交于 2019-11-26 15:58:16
问题 I've inherited a database that wasn't designed exactly optimally, and I need to manipulate some data. Let me give a more common analogy of the kind of thing I have to do: Let's say we have a Student table, a StudentClass table keeping record of all the classes he attended, and a StudentTeacher table that stores all the teachers who taught this student. Yes, I know it's a dumb design and it would make more sense to store the teacher on the Class table - but that's what we're working with. I

SQL SELECT from multiple tables

由 拜拜、爱过 提交于 2019-11-26 12:03:26
问题 How can I get all products from customers1 and customers2 include their customer names? customer1 table cid name1 1 john 2 joe customer2 table cid name2 p1 sandy p2 linda product table pid cid pname 1 1 phone 2 2 pencil 3 p1 pen 4 p2 paper Result should be like this pid cid pname name1 name2 1 1 phone john NULL 2 2 pencil joe NULL 3 p1 pen NULL sandy 4 p2 paper NULL linda 回答1: SELECT p.pid, p.cid, p.pname, c1.name1, c2.name2 FROM product p LEFT JOIN customer1 c1 ON p.cid = c1.cid LEFT JOIN

Oracle (Old?) Joins - A tool/script for conversion?

由 强颜欢笑 提交于 2019-11-26 09:13:49
问题 I have been porting oracle selects, and I have been running across a lot of queries like so: SELECT e.last_name, d.department_name FROM employees e, departments d WHERE e.department_id(+) = d.department_id; ...and: SELECT last_name, d.department_id FROM employees e, departments d WHERE e.department_id = d.department_id(+); Are there any guides/tutorials for converting all of the variants of the (+) syntax? What is that syntax even called (so I can scour google)? Even better .. Is there a tool
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