What is difference between INNER join and OUTER join [duplicate]
This is the best and simplest way to understand joins: Credits go to the writer of this article HERE
This is the best and simplest way to understand joins: Credits go to the writer of this article HERE
Use: SELECT x.name, GROUP_CONCAT(y.property SEPARATOR ‘, ‘) FROM PEOPLE x LEFT JOIN PROPERTIES y ON y.name = x.name WHERE x.age > 26 GROUP BY x.name You want the MySQL function GROUP_CONCAT (documentation) in order to return a comma separated list of the PROPERTIES.property value. I used a LEFT JOIN rather than a JOIN in order … Read more
There are several ways, but I think the following is the most popular: select allk.k, t1.c1, t2.v2, t3.v3, t4.v4 from (select k from t1 union select k from t2 union select k from t3 union select k from t4 ) allk left outer join t1 on allk.k = t1.k left outer join t2 on allk.k … Read more
Pipe the array to the Out-String cmdlet to convert them from a collection of string objects to a single string: PS> $body = $invalid_hosts -join “`r`n” | Out-String
I have done this join so many times that I could not figure out why it would not work until I found a post from Justin Niessner here that says “The names of the properties in the anonymous types (as well as their types) must match exactly.” That lead me to this code: using(var db … Read more
Use nested joins Employer.joins({:people => {:household => {:suburb => :city}}}) should give you the join table you’re looking. If you were traversing the other direction you would use plural names City.joins( :suburbs => {:households => {:people => :employers }})
models.products.findAll({ include: [ {model: models.comments, include: [models.comments.users] } ] })
You can use AND in the expression for the ON criteria and demand the fields are all equal there. SELECT * FROM Table1 INNER JOIN Table2 ON Table1.Key1 = Table2.Key1 AND Table1.Key2 = Table2.Key2 AND Table1.Key3 = Table2.Key3
Typically, you would use NOT EXISTS for this type of query SELECT p.Name FROM pooltest p WHERE NOT EXISTS (SELECT s.Name FROM senttest s WHERE s.Name = p.Name) An alternative would be to use a LEFT OUTER JOIN and check for NULL SELECT p.Name FROM pooltest p LEFT OUTER JOIN senttest s ON s.Name = … Read more