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SQL join: selecting the last records in a one-to-many relationship
...mmend solving it:
SELECT c.*, p1.*
FROM customer c
JOIN purchase p1 ON (c.id = p1.customer_id)
LEFT OUTER JOIN purchase p2 ON (c.id = p2.customer_id AND
(p1.date < p2.date OR (p1.date = p2.date AND p1.id < p2.id)))
WHERE p2.id IS NULL;
Explanation: given a row p1, there should be no ro...
How to use ScrollView in Android?
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Just make the top-level layout a ScrollView:
<ScrollView xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:fillViewport="true">
<TableLayout
android:layout_width="match_par...
How to create relationships in MySQL
...e innodb you can create it like this:
CREATE TABLE accounts(
account_id INT NOT NULL AUTO_INCREMENT,
customer_id INT( 4 ) NOT NULL ,
account_type ENUM( 'savings', 'credit' ) NOT NULL,
balance FLOAT( 9 ) NOT NULL,
PRIMARY KEY ( account_id ),
FOREIGN KEY (customer_id) REFERE...
Naming of ID columns in database tables
I was wondering peoples opinions on the naming of ID columns in database tables.
24 Answers
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Surrogate vs. natural/business keys [closed]
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If you have multiple "candidate" keys (fields or same-size collections of fields that are NOT NULL UNIQUE) then you are likely in violation of Boyce-Codd Normal Form. BCNF is beyond 3NF, so not many people worry about it. There are situations, howev...
Insert Update trigger how to determine if insert or update
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Obviously, DELETE triggers can not have "always rows in INSERTED" as I said above
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PostgreSQL delete with inner join
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DELETE
FROM m_productprice B
USING m_product C
WHERE B.m_product_id = C.m_product_id AND
C.upc = '7094' AND
B.m_pricelist_version_id='1000020';
or
DELETE
FROM m_productprice
WHERE m_pricelist_version_id='1000020' AND
m_product_id IN (SELECT m_product...
Are class names in CSS selectors case sensitive?
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CSS selectors are generally case-insensitive; this includes class and ID selectors.
But HTML class names are case-sensitive (see the attribute definition), and that's causing a mismatch in your second example. This has not changed in HTML5.1
This is because the case-sensitivity of selectors i...
How to create a date and time picker in Android? [closed]
Is there any android widget that enable to pick the date and the time at the same time ?
I already use the basic time picker and date picker .
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How to check a checkbox in capybara?
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I found the following worked for me:
# Check
find(:css, "#cityID[value='62']").set(true)
# Uncheck
find(:css, "#cityID[value='62']").set(false)
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