大约有 40,000 项符合查询结果（耗时：0.0231秒） [XML]
Best practices for SQL varchar column length [closed]
Every time is set up a new SQL table or add a new varchar column to an existing table, I am wondering one thing: what is the best value for the length .
...
MySQL ON vs USING?
...fferences are noteworthy:
ON is the more general of the two. One can join tables ON a column, a set of columns and even a condition. For example:
SELECT * FROM world.City JOIN world.Country ON (City.CountryCode = Country.Code) WHERE ...
USING is useful when both tables share a column of the exac...
In MySQL queries, why use join instead of where?
It seems like to combine two or more tables, we can either use join or where. What are the advantages of one over the other?
...
What's the bad magic number error?
...or run the command above, after verifying you're not doing something regrettable.
– michael
Aug 11 '16 at 23:45
9
...
ERROR 1045 (28000): Access denied for user 'root'@'localhost' (using password: YES)
...ysql.server stop
Start it in safe mode:
$ sudo mysqld_safe --skip-grant-tables --skip-networking
(above line is the whole command)
This will be an ongoing command until the process is finished so open another shell/terminal window, log in without a password:
$ mysql -u root
mysql> UPDATE ...
How Can I Set the Default Value of a Timestamp Column to the Current Timestamp with Laravel Migratio
... use DB::raw() to set CURRENT_TIMESTAMP as a default value for a column:
$table->timestamp('created_at')->default(DB::raw('CURRENT_TIMESTAMP'));
This works flawlessly on every database driver.
New shortcut
As of Laravel 5.1.25 (see PR 10962 and commit 15c487fe) you can use the new useCurr...
Error Code: 1005. Can't create table '…' (errno: 150)
...T(11) or TINYINT. You may want to confirm the field size using SHOW CREATE TABLE because Query Browser will sometimes visually show just INTEGER for both INT(10) and INT(11). You should also check that one is not SIGNED and the other is UNSIGNED. They both need to be exactly the same.
One of the key...
Create a nonclustered non-unique index within the CREATE TABLE statement with SQL Server
...ossible to create a primary key or unique index within a SQL Server CREATE TABLE statement. Is it possible to create a non-unique index within a CREATE TABLE statement?
...
How do I change the data type for a column in MySQL?
...
http://dev.mysql.com/doc/refman/5.1/en/alter-table.html
ALTER TABLE tablename MODIFY columnname INTEGER;
This will change the datatype of given column
Depending on how many columns you wish to modify it might be best to generate a script, or use some kind of mysql clie...
Add primary key to existing table
I have an existing table called Persion . In this table I have 5 columns:
10 Answers
...