大约有 16,000 项符合查询结果（耗时：0.0207秒） [XML]
What is the difference between ExecuteScalar, ExecuteReader and ExecuteNonQuery?
...the first row. An example might be SELECT @@IDENTITY AS 'Identity'.
ExecuteReader is used for any result set with multiple rows/columns (e.g., SELECT col1, col2 from sometable).
ExecuteNonQuery is typically used for SQL statements without results (e.g., UPDATE, INSERT, etc.).
...
What's the difference between an inverted index and a plain old index?
...ere is absolutely no difference between them.
For the benefit of future readers, I will now provide several "forward" and "inverted" index examples:
Example 1: Web search
If you're thinking that the inverse of an index is something like the inverse of a function in mathematics, where the invers...
Volatile boolean vs AtomicBoolean
...le integer:
volatile int i = 0;
void incIBy5() {
i += 5;
}
If two threads call the function concurrently, i might be 5 afterwards, since the compiled code will be somewhat similar to this (except you cannot synchronize on int):
void incIBy5() {
int temp;
synchronized(i) { temp = i }
...
Dynamic variable names in Bash
...n indirection variable, not unlike a C pointer. Bash then has a syntax for reading the aliased variable: ${!name} expands to the value of the variable whose name is the value of the variable name. You can think of it as a two-stage expansion: ${!name} expands to $var_37, which expands to lolilol.
na...
Why is this inline-block element pushed downward?
...o grasp the idea of line boxes and how they are lined in the same line esp read last paragraph carefully because there lies the answer of your question.
The baseline of an 'inline-block' is the baseline of its last line box in the normal flow, unless it has either no in-flow line boxes or if its...
Reading a string with scanf
...nfused about something. I was under the impression that the correct way of reading a C string with scanf() went along the lines of
...
How do I use valgrind to find memory leaks?
...etc.
sudo yum install valgrind # RHEL, CentOS, Fedora, etc.
Valgrind is readily usable for C/C++ code, but can even be used for other
languages when configured properly (see this for Python).
To run Valgrind, pass the executable as an argument (along with any
parameters to the program).
valgr...
What are the differences between the threading and multiprocessing modules?
I am learning how to use the threading and the multiprocessing modules in Python to run certain operations in parallel and speed up my code.
...
How to create “No Activate” form in Firemonkey
...Form: TForm);
destructor Destroy; override;
property Left: Integer read GetLeft write SetLeft;
property Top: Integer read GetTop write SetTop;
property Height: Integer read GetHeight write SetHeight;
property Width: Integer read GetWidth write SetWidth;
property Visible: Bool...
How to write a foreach in SQL Server?
...at:
DECLARE @PractitionerId int
DECLARE MY_CURSOR CURSOR
LOCAL STATIC READ_ONLY FORWARD_ONLY
FOR
SELECT DISTINCT PractitionerId
FROM Practitioner
OPEN MY_CURSOR
FETCH NEXT FROM MY_CURSOR INTO @PractitionerId
WHILE @@FETCH_STATUS = 0
BEGIN
--Do something with Id here
PRINT @Practitio...