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How can I view live MySQL queries?
... As far as I can tell, there is no way to trigger anything on a SELECT statement. Triggers only apply to INSERT, UPDATE, DELETE... or am I misinformed?
– gabe.
Dec 8 '11 at 21:14
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MySQL: selecting rows where a column is null
I'm having a problem where when I try to select the rows that have a NULL for a certain column, it returns an empty set. However, when I look at the table in phpMyAdmin, it says null for most of the rows.
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How to select records from last 24 hours using SQL?
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SELECT *
FROM table_name
WHERE table_name.the_date > DATE_SUB(CURDATE(), INTERVAL 1 DAY)
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Combine two ActiveRecord::Relation objects
...name_relation.merge(last_name_relation)
If you want to combine using OR (union), use or†:
first_name_relation.or(last_name_relation)
† Only in ActiveRecord 5+; for 4.2 install the where-or backport.
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How to get the next auto-increment id in mysql
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You can use
SELECT AUTO_INCREMENT
FROM information_schema.tables
WHERE table_name = 'table_name'
AND table_schema = DATABASE( ) ;
or if you do not wish to use information_schema you can use this
SHOW TABLE STATUS LIKE 'table_name'
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MySQL connection not working: 2002 No such file or directory
I'm trying to set up WordPress. I have Apache and MySQL running, and the accounts and database are all set up. I tried to make a simple connection:
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How to 'insert if not exists' in MySQL?
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Solution:
INSERT INTO `table` (`value1`, `value2`)
SELECT 'stuff for value1', 'stuff for value2' FROM DUAL
WHERE NOT EXISTS (SELECT * FROM `table`
WHERE `value1`='stuff for value1' AND `value2`='stuff for value2' LIMIT 1)
Explanation:
The innermost query
SELECT *...
Mysql: Select rows from a table that are not in another
How to select all rows in one table that do not appear on another?
8 Answers
8
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Elegant way to combine multiple collections of elements?
...in a collection (e.g., of type List<List<int>> , I could use SelectMany to combine them all into one collection.
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How do I check if a column is empty or null in MySQL?
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This will select all rows where some_col is NULL or '' (empty string)
SELECT * FROM table WHERE some_col IS NULL OR some_col = '';
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