大约有 42,000 项符合查询结果（耗时：0.0153秒） [XML]
Which method performs better: .Any() vs .Count() > 0?
...re generated SQLs. Beauties as you can see ;)
ANY:
exec sp_executesql N'SELECT TOP (1)
[Project2].[ContactId] AS [ContactId],
[Project2].[CompanyId] AS [CompanyId],
[Project2].[ContactName] AS [ContactName],
[Project2].[FullName] AS [FullName],
[Project2].[ContactStatusId] AS [ContactStatusI...
How enumerate all classes with custom class attribute?
... faster (especially without empirical proof); you've basically written the Select extension method, and the compiler will generate a state machine just as it would if you called Select because of your use of yield return. Finally, any performance gains that might be obtained in the majority of case...
PostgreSQL return result set as JSON array?
...
TL;DR
SELECT json_agg(t) FROM t
for a JSON array of objects, and
SELECT
json_build_object(
'a', json_agg(t.a),
'b', json_agg(t.b)
)
FROM t
for a JSON object of arrays.
List of objects
This section de...
Find a value anywhere in a database
...OT NULL
BEGIN
SET @ColumnName = ''
SET @TableName =
(
SELECT MIN(QUOTENAME(TABLE_SCHEMA) + '.' + QUOTENAME(TABLE_NAME))
FROM INFORMATION_SCHEMA.TABLES
WHERE TABLE_TYPE = 'BASE TABLE'
AND QUOTENAME(TABLE_SCHEMA) + '.' + QUOTENAME(TABLE_NAME) &...
How do I specify a pointer to an overloaded function?
...putIterator, InputIterator, UnaryFunction );
Template deduction needs to select a type for UnaryFunction at the point of the call. But f doesn't have a specific type - it's an overloaded function, there are many fs each with different types. There is no current way for for_each to aid the template...
Turning a Comma Separated string into individual rows
... SomeID INT,
OtherID INT,
String VARCHAR(MAX)
)
INSERT Testdata SELECT 1, 9, '18,20,22'
INSERT Testdata SELECT 2, 8, '17,19'
INSERT Testdata SELECT 3, 7, '13,19,20'
INSERT Testdata SELECT 4, 6, ''
INSERT Testdata SELECT 9, 11, '1,2,3,4'
The query
;WITH tmp(SomeID, OtherID, DataIt...
What are the use cases for selecting CHAR over VARCHAR in SQL?
...'123 Main St Washington, MD 12345', 123.45)
create view vwStagingTable AS
SELECT CustomerFirstName = CAST(CustomerFirstName as CHAR(30)),
CustomerLastName = CAST(CustomerLastName as CHAR(30)),
CustomerCityStateZip = CAST(CustomerCityStateZip as CHAR(100)),
CustomerCurrentBalance = CAST(CAST(Custome...
How to use GROUP BY to concatenate strings in SQL Server?
...S (1,'B',8)
INSERT INTO #YourTable ([ID],[Name],[Value]) VALUES (2,'C',9)
SELECT
[ID],
STUFF((
SELECT ', ' + [Name] + ':' + CAST([Value] AS VARCHAR(MAX))
FROM #YourTable
WHERE (ID = Results.ID)
FOR XML PATH(''),TYPE).value('(./text())[1]','VARCHAR(MAX)')
,1,2,'') AS NameVa...
How to create a SQL Server function to “join” multiple rows from a subquery into a single delimited
...
If you're using SQL Server 2005, you could use the FOR XML PATH command.
SELECT [VehicleID]
, [Name]
, (STUFF((SELECT CAST(', ' + [City] AS VARCHAR(MAX))
FROM [Location]
WHERE (VehicleID = Vehicle.VehicleID)
FOR XML PATH ('')), 1, 2, '')) AS Locations
FROM [...
SQL: IF clause within WHERE clause
... THEN '%' + @OrderNumber
ELSE ''
END
2) Use IF's outside the SELECT
IF (IsNumeric(@OrderNumber)) = 1
BEGIN
SELECT * FROM Table
WHERE @OrderNumber = OrderNumber
END ELSE BEGIN
SELECT * FROM Table
WHERE OrderNumber LIKE '%' + @OrderNumber
END
3) Using a long string, co...