大约有 43,000 项符合查询结果（耗时：0.0420秒） [XML]
Why is an array not assignable to Iterable?
...able forces adding an iterator method, and arrays don't implement methods. char[] doesn't even override toString. Anyway, arrays of references should be considered less than ideal - use Lists. As dfa comments, Arrays.asList will do the conversion for you, explicitly.
(Having said that, you can call...
Get the last inserted row ID (with SQL statement) [duplicate]
...alue using:
INSERT INTO dbo.YourTable(columns....)
VALUES(..........)
SELECT SCOPE_IDENTITY()
This works as long as you haven't inserted another row - it just returns the last IDENTITY value handed out in this scope here.
There are at least two more options - @@IDENTITY and IDENT_CURRENT - r...
How to check if a column exists in a SQL Server table?
...
SQL Server 2005 onwards:
IF EXISTS(SELECT 1 FROM sys.columns
WHERE Name = N'columnName'
AND Object_ID = Object_ID(N'schemaName.tableName'))
BEGIN
-- Column Exists
END
Martin Smith's version is shorter:
IF COL_LENGTH('schemaName.tabl...
Why do we always prefer using parameters in SQL statements?
I am very new to working with databases. Now I can write SELECT , UPDATE , DELETE , and INSERT commands. But I have seen many forums where we prefer to write:
...
Regex (grep) for multi-line search needed [duplicate]
I'm running a grep to find any *.sql file that has the word select followed by the word customerName followed by the word from . This select statement can span many lines and can contain tabs and newlines.
...
C#: How to convert a list of objects to a list of a single property of that object?
...
List<string> firstNames = people.Select(person => person.FirstName).ToList();
And with sorting
List<string> orderedNames = people.Select(person => person.FirstName).OrderBy(name => name).ToList();
...
SQL JOIN vs IN performance?
...king, IN and JOIN are different queries that can yield different results.
SELECT a.*
FROM a
JOIN b
ON a.col = b.col
is not the same as
SELECT a.*
FROM a
WHERE col IN
(
SELECT col
FROM b
)
, unless b.col is unique.
However, this is the syno...
Acronyms in CamelCase [closed]
...n using acronyms, use Pascal case or camel case for acronyms more than two characters long. For example, use HtmlButton or htmlButton. However, you should capitalize acronyms that consist of only two characters, such as System.IO instead of System.Io.
Do not use abbreviations in identifiers or ...
Swapping column values in MySQL
...rows affected (0.08 sec)
Records: 4 Duplicates: 0 Warnings: 0
mysql> SELECT * FROM swaptest;
+------+------+
| X | Y |
+------+------+
| 1 | 2 |
| 3 | 4 |
| -5 | -8 |
| -13 | 27 |
+------+------+
4 rows in set (0.00 sec)
mysql>
Here is the swap being performed
m...
LINQ query on a DataTable
...w in myDataTable.AsEnumerable()
where myRow.Field<int>("RowNo") == 1
select myRow;
And as @Keith says, you'll need to add a reference to System.Data.DataSetExtensions
AsEnumerable() returns IEnumerable<DataRow>. If you need to convert IEnumerable<DataRow> to a DataTable, use the...