大约有 7,000 项符合查询结果（耗时：0.0174秒） [XML]
What is the size of column of int(11) in mysql in bytes?
What is the size of column of int(11) in mysql in bytes?
11 Answers
11
...
Can you use an alias in the WHERE clause in mysql?
...will not work, in which case you'll need to use a HAVING clause.
From the MySQL Manual:
It is not allowable to refer to a
column alias in a WHERE clause,
because the column value might not yet
be determined when the WHERE clause
is executed. See Section B.1.5.4,
“Problems with Colu...
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
...
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
...
When to use MyISAM and InnoDB? [duplicate]
...
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 ...
Alter MySQL table to add comments on columns
I have been checking the MySQL Documentation for ALTER TABLE and it does not seem to include a way to add or modify a comment to a column. How can I do this?
...
MySQL Orderby a number, Nulls last
...
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
...
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.
...
Set NOW() as Default Value for datetime datatype?
...
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...