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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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How do I select an entire row which has the largest ID in the table?
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You could use a subselect:
SELECT row
FROM table
WHERE id=(
SELECT max(id) FROM table
)
Note that if the value of max(id) is not unique, multiple rows are returned.
If you only want one such row, use @MichaelMior's answer,
SELECT row from table ORDER BY id DESC LIMIT...
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 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...
Array vs. Object efficiency in JavaScript
...icient way of storing them and retrieving a single object once I have it's id. The id's are long numbers.
9 Answers
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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...
ORDER BY the IN value list
...a simple SQL query in PostgreSQL 8.3 that grabs a bunch of comments. I provide a sorted list of values to the IN construct in the WHERE clause:
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How to UPSERT (MERGE, INSERT … ON DUPLICATE UPDATE) in PostgreSQL?
...em in useful detail.
In general you must choose between two options:
Individual insert/update operations in a retry loop; or
Locking the table and doing batch merge
Individual row retry loop
Using individual row upserts in a retry loop is the reasonable option if you want many connections concurre...
How to debug Lock wait timeout exceeded on MySQL?
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What gives this away is the word transaction. It is evident by the statement that the query was attempting to change at least one row in one or more InnoDB tables.
Since you know the query, all the tables being accessed are candidates for being the culprit.
From there, you shou...
How to get the device's IMEI/ESN programmatically in android?
To identify each devices uniquely I would like to use the IMEI (or ESN number for CDMA devices). How to access this programmatically?
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