大约有 47,000 项符合查询结果（耗时：0.0310秒） [XML]
Recommended SQL database design for tags or tagging [closed]
...ries which you will do: Output all Tags for one Item, draw a Tag-Cloud and select all items for one Tag Title.
All Tags for one Item:
3-Table:
SELECT Tag.Title
FROM Tag
JOIN ItemTag ON Tag.TagID = ItemTag.TagID
WHERE ItemTag.ItemID = :id
2-Table:
SELECT Tag.Title
FROM Tag
WHERE Tag.Item...
What is LINQ and what does it do? [closed]
...;string> result =
from c in myCustomers
where c.Name.StartsWith("B")
select c.Name;
Lambda Expressions - This is a shorthand for specifying a method. The C# compiler will translate each into either an anonymous method or a true System.Linq.Expressions.Expression. You really need to understand...
SQL left join vs multiple tables on FROM line?
...nts that have employees, but always list all companies.
So you do this:
SELECT * -- for simplicity
FROM Company, Department, Employee
WHERE Company.ID *= Department.CompanyID
AND Department.ID = Employee.DepartmentID
Note that the last one there is an inner join, in order to fulfill the crite...
SQL order string as number
...u can't do that then cast your column value to an integer explicitly with
select col from yourtable
order by cast(col as unsigned)
or implicitly for instance with a mathematical operation which forces a conversion to number
select col from yourtable
order by col + 0
BTW MySQL converts strings...
What's the difference between a temp table and table variable in SQL Server?
...-unique indexes too.
Table variables don't participate in transactions and SELECTs are implicitly with NOLOCK. The transaction behaviour can be very helpful, for instance if you want to ROLLBACK midway through a procedure then table variables populated during that transaction will still be populated...
Laravel Eloquent groupBy() AND also return count of each group
...working for me:
$user_info = DB::table('usermetas')
->select('browser', DB::raw('count(*) as total'))
->groupBy('browser')
->get();
share
|
...
Pycharm: run only part of my Python file
... easier way.
go to File -> Settings -> Keymap
Search for Execute Selection in Console and reassign it to a new shortcut, like Crl + Enter.
This is the same shortcut to the same action in Spyder and R-Studio.
sha...
How do I check if a Sql server string is null or empty
...
I think this:
SELECT
ISNULL(NULLIF(listing.Offer_Text, ''), company.Offer_Text) AS Offer_Text
FROM ...
is the most elegant solution.
And to break it down a bit in pseudo code:
// a) NULLIF:
if (listing.Offer_Text == '')
temp := nu...
UPDATE multiple tables in MySQL using LEFT JOIN
...= t1.id
SET t1.col1 = newvalue
WHERE t2.id IS NULL
Note that for a SELECT it would be more efficient to use NOT IN / NOT EXISTS syntax:
SELECT t1.*
FROM t1
WHERE t1.id NOT IN
(
SELECT id
FROM t2
)
See the article in my blog for performance details...
Querying data by joining two tables in two database on different servers
...just prefixing the database name with the other server. I.E:
-- FROM DB1
SELECT *
FROM [MyDatabaseOnDB1].[dbo].[MyTable] tab1
INNER JOIN [DB2].[MyDatabaseOnDB2].[dbo].[MyOtherTable] tab2
ON tab1.ID = tab2.ID
Once the link is established, you can also use OPENQUERY to execute a SQL st...