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Checking for an empty field with MySQL
...)" and there's one record with null hotline but it doesn't match.I'm using MySQL 5.6
– Scott Chu
Apr 15 '16 at 10:16
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Adding multiple columns AFTER a specific column in MySQL
...ermitted in a single ALTER TABLE statement, separated by commas. This is a MySQL extension to standard SQL, which permits only one of each clause per ALTER TABLE statement.
– informatik01
May 1 '19 at 13:21
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When to use MyISAM and InnoDB? [duplicate]
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Read about Storage Engines.
MyISAM:
The MyISAM storage engine in MySQL.
Simpler to design and create, thus better for beginners. No worries about the foreign relationships between tables.
Faster than InnoDB on the whole as a result of the simpler structure thus much less costs of server ...
ROW_NUMBER() in MySQL
Is there a nice way in MySQL to replicate the SQL Server function ROW_NUMBER() ?
24 Answers
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MySQL Orderby a number, Nulls last
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MySQL has an undocumented syntax to sort nulls last. Place a minus sign (-) before the column name and switch the ASC to DESC:
SELECT * FROM tablename WHERE visible=1 ORDER BY -position DESC, id DESC
It is essentially the...
How to update column with null value
I am using mysql and need to update a column with a null value. I have tried this many different ways and the best I have gotten is an empty string.
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Why does MYSQL higher LIMIT offset slow the query down?
...30
) q
JOIN mytable t
ON t.id = q.id
See this article:
MySQL ORDER BY / LIMIT performance: late row lookups
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Set NOW() as Default Value for datetime datatype?
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As of MySQL 5.6.5, you can use the DATETIME type with a dynamic default value:
CREATE TABLE foo (
creation_time DATETIME DEFAULT CURRENT_TIMESTAMP,
modification_time DATETIME ON UPDATE CURRENT_TIMESTAMP
)
Or even...
MySQL - Make an existing Field Unique
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ALTER IGNORE TABLE mytbl ADD UNIQUE (columnName);
For MySQL 5.7.4 or later:
ALTER TABLE mytbl ADD UNIQUE (columnName);
As of MySQL 5.7.4, the IGNORE clause for ALTER TABLE is removed and
its use produces an error.
So, make sure to remove duplicate entries first as IGNO...
MySQL: Quick breakdown of the types of joins [duplicate]
I would like a quick breakdown of the types of MySQL joins. I know of these, the rest I am not sure what they mean.
3 Answe...