大约有 40,000 项符合查询结果（耗时：0.0212秒） [XML]
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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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...
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...
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...
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...
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...
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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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...
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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Using querySelector with IDs that are numbers
From what I understand the HTML5 spec lets you use IDs that are numbers like this.
5 Answers
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