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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...
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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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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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...
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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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 selecting yesterday's date
... would otherwise require a cumbersome and wordy case statement, is that in mysql boolean values are 1 for true and 0 for false, so summing a condition effectively counts how many times it's true. Using this pattern can neaten up your SQL code.
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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...
MySQL: selecting rows where a column is null
...E userid = NULL;
This will not give you the expected result, because from mysql doc
In SQL, the NULL value is never true in comparison to any other value, even NULL. An expression that contains NULL always produces a NULL value unless otherwise indicated in the documentation for the operators and ...
How can I make SQL case sensitive string comparison on MySQL?
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http://dev.mysql.com/doc/refman/5.0/en/case-sensitivity.html
The default character set and collation are latin1 and latin1_swedish_ci, so nonbinary string comparisons are case insensitive by default. This means that if you search wi...