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How to select all records from one table that do not exist in another table?
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SELECT t1.name
FROM table1 t1
LEFT JOIN table2 t2 ON t2.name = t1.name
WHERE t2.name IS NULL
Q: What is happening here?
A: Conceptually, we select all rows from table1 and for each row we attempt to find a row in table2 with the same value for ...
Why is the minimalist, example Haskell quicksort not a “true” quicksort?
Haskell's website introduces a very attractive 5-line quicksort function , as seen below.
11 Answers
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How to pass a function as a parameter in Java? [duplicate]
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Java 8 and above
Using Java 8+ lambda expressions, if you have a class or interface with only a single abstract method (sometimes called a SAM type), for example:
public interface MyInterface {
String doSomething(int param1, String...
How does comparison operator works with null int?
I am starting to learn nullable types and ran into following behavior.
4 Answers
4
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How do you delete a column by name in data.table?
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Any of the following will remove column foo from the data.table df3:
# Method 1 (and preferred as it takes 0.00s even on a 20GB data.table)
df3[,foo:=NULL]
df3[, c("foo","bar"):=NULL] # remove two columns
myVar = "foo"
df3[, (myVar):=NULL] # lookup myVar contents
# Method 2a --...
When should I make explicit use of the `this` pointer?
When should I explicitly write this->member in a method of
a class?
12 Answers
12...
Possible to iterate backwards through a foreach?
I know I could use a for statement and achieve the same effect, but can I loop backwards through a foreach loop in C#?
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How to repair a serialized string which has been corrupted by an incorrect byte count length?
... in serialized array
You current serialized data
$data = 'a:10:{s:16:"submit_editorial";b:0;s:15:"submit_orig_url";s:13:"www.bbc.co.uk";s:12:"submit_title";s:14:"No title found";s:14:"submit_content";s:12:"dnfsdkfjdfdf";s:15:"submit_category";i:2;s:11:"submit_tags";s:3:"bbc";s:9:"submit_id";b:0;s...
how to reference a YAML “setting” from elsewhere in the same YAML file?
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I don't think it is possible. You can reuse "node" but not part of it.
bill-to: &id001
given : Chris
family : Dumars
ship-to: *id001
This is perfectly valid YAML and fields given and family are reused in ship-to block. You can reuse ...
Select datatype of the field in postgres
How do I get datatype of specific field from table in postgres ?
For example
I have the following table,
student_details (
stu_id integer,
stu_name varchar(30 ),
joined_date timestamp
);
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