outer-join

问题 I'm trying to learn the the ansi-92 SQL standard, but I don't seem to understand it completely (I'm new to the ansi-89 standard as well and in databases in general). In my example, I have three tables kingdom -< family -< species (biology classifications). There may be kingdoms without species nor families. There may be families without species nor kindgoms. There may be species without kingdom or families. Why this may happen? Say a biologist, finds a new species but he has not classified

问题 I have two tables customer_details and address_details . I want to display customer details with their corresponding address, so I was using a LEFT JOIN , but when I'm executing this query, SQL Server drops rows where street_no of customer_details table doesn't match with the street_no in address_detials table and displays only rows where `street_no' of customer_detials = street_no of address_details table. I need to display a complete customer_details table and in case if street_no doesn't

问题 I have two tables, t1 and t2: t1 person | visit | code1 | type1 1 1 50 50 1 1 50 50 1 2 75 50 t2 person | visit | code2 | type2 1 1 50 50 1 1 50 50 1 1 50 50 When SAS runs the following code: DATA t3; MERGE t1 t2; BY person visit; RUN; It generates the following dataset: person | visit | code1 | type1 | code2 | type2 1 1 50 50 50 50 1 1 50 50 50 50 1 1 50 50 50 50 1 2 75 50 I want to replicate this process in SQL, and my idea was to use a full-outer-join. This works unless there are duplicate

问题 I have a hibernate mapping like this in a ProductDfn class @ManyToOne( fetch = FetchType.LAZY, optional = true ) @JoinColumn( name = "productTypeFk", nullable = true ) public ProductType getProductType() { return productType; } Note that the relationship is defined as optional (and the column is nullable). When doing HQL something like this select p.name as col1, p.productType.name as col2 from ProductDfn p An inner join is used to join ProductDfn to ProductType as hibernate generates the

问题 Using MySQL 5.x I want to efficiently select all rows from table X where there is no related row in table Y satisfying some condition, e.g. Give me all records in X where a related Y with foo = bar does NOT exist SELECT count(id) FROM X LEFT OUTER JOIN Y ON y.X_id = X.id AND y.foo = 'bar' WHERE y....? As I understand it, a left outer join is guaranteed to produce a row for each row in the left (first) table -- X in this case -- whether or not a satisfying row in the joined table was found.

问题 I'm having a problem moving from a situation where an Outer Join works, to where it fails. Working (pseudo code example) SELECT a.number, a.name, b.ref, c.ref, c.firmref FROM jobs a, teams b LEFT OUTER JOIN teamfirms c ON b.ref = c.team WHERE a.ref = b.job There is a many to one relationship between jobs and teams (many teams per job) that is always populated There may or may not be firms in table c, but the query above gives me the result I would expect (approx 5000 records) The problem

问题 I am trying to do Full Outer Join on 4 Hive tables. The JOIN key is same, but the schema of the 4 tables are different. I want to generate all the column values for all the ids present in the 4 tables. But the id column should be present only once with all values included, not 4 times(each from one table) Query 1 select count(*) from table1 f FULL OUTER JOIN table2 u on f.id=u.id FULL OUTER JOIN table3 v on f.id=v.id FULL OUTER JOIN table4 v_in on f.id=v_in.id; Count=2787037 Query 2 select

问题 I have come across the following legacy PL/SQL and find the outer joins against scalar constants somewhat confusing. First of all, can someone please confirm that my attempt to convert this to ANSI is correct. LEGACY CODE : cursor c1item (c1item_iel_id number) is select `<columns>` from iel_item iit, iel_item_property iip where iit.iit_change_type = 'I' and iip.iip_change_type (+) = 'I' and iip.it_id (+) = iit.it_id and iit.iel_id = c1item_iel_id and iip.iel_id (+) = c1item_iel_id; ANSI CODE

问题 We're trying to run an outer join between table A on both tables B and C but get the error: ORA-01417: a table may be outer joined to at most one other table How can we get this to work? Query: select a.xxx, a.yyy, b.col1, c.col1 from a, b, c where a.xxx = b.xxx (+) and a.yyy = b.yyy (+) and a.xxx = c.xxx (+) and a.yyy = c.yyy (+) 回答1: Please refrain from using comma in the from clause and use the JOIN clause instead. Try using this: select a.xxx, a.yyy, b.col1, c.col1 from a LEFT JOIN b ON a

问题 I'm trying to filter out a table using filter in the outer join clause rather than a where clause. When i try to do so i'm getting unexpected results. The whole table is returned as though i didn't apply the filter at all. When I run this example, i get different results for the last two queries. I would expect them to have the same results but it's not the case. What is going on here? declare @a table ( id int ,content varchar(100) ) declare @b table ( id int ,content varchar(100) ) insert