大约有 40,000 项符合查询结果（耗时：0.0268秒） [XML]
Throw an error in a MySQL trigger
... trigger_test values (1), (-1), (2); -- everything fails as one row is bad
select * from trigger_test;
insert into trigger_test values (1); -- succeeds as expected
insert into trigger_test values (-1); -- fails as expected
select * from trigger_test;
...
How to convert a char to a String?
I have a char and I need a String . How do I convert from one to the other?
12 Answers
...
What's the difference between __PRETTY_FUNCTION__, __FUNCTION__, __func__?
...
__func__ is an implicitly declared identifier that expands to a character array variable containing the function name when it is used inside of a function. It was added to C in C99. From C99 §6.4.2.2/1:
The identifier __func__ is implicitly declared by the translator as if, immediatel...
How to determine CPU and memory consumption from inside a process?
...hysMemUsedByMe = pmc.WorkingSetSize;
CPU currently used:
#include "TCHAR.h"
#include "pdh.h"
static PDH_HQUERY cpuQuery;
static PDH_HCOUNTER cpuTotal;
void init(){
PdhOpenQuery(NULL, NULL, &cpuQuery);
// You can also use L"\\Processor(*)\\% Processor Time" and get individual CPU...
How can I pad an int with leading zeros when using cout
...) << 25;
}
the output will be
00025
setfill is set to the space character (' ') by default. setw sets the width of the field to be printed, and that's it.
If you are interested in knowing how the to format output streams in general, I wrote an answer for another question, hope it is us...
What is the list of supported languages/locales on Android?
...ble for application development (they may not necessarily be available for selection in a given device's system settings, though). When using ISO 639-1 codes, the resource folder has the format values-xx... where xx is the ISO-639-1 code.
When using BCP 47 tags, the resource folder is named valu...
Parameterize an SQL IN clause
...
Here's a quick-and-dirty technique I have used:
SELECT * FROM Tags
WHERE '|ruby|rails|scruffy|rubyonrails|'
LIKE '%|' + Name + '|%'
So here's the C# code:
string[] tags = new string[] { "ruby", "rails", "scruffy", "rubyonrails" };
const string cmdText = "select * from t...
Maximum number of characters using keystrokes A, Ctrl+A, Ctrl+C and Ctrl+V
...rate through for i up to n, doing two things: pressing A once and pressing select all + copy followed by paste j times (actually j-i-1 below; note the trick here: the contents are still in the clipboard, so we can paste it multiple times without copying each time). We only have to consider up to 4 c...
How much is the overhead of smart pointers compared to normal pointers in C++?
...ude <thread>
uint32_t n = 100000000;
void t_m(void){
auto a = (char*) malloc(n*sizeof(char));
for(uint32_t i=0; i<n; i++) a[i] = 'A';
}
void t_u(void){
auto a = std::unique_ptr<char[]>(new char[n]);
for(uint32_t i=0; i<n; i++) a[i] = 'A';
}
void t_u2(void){
a...
What are the main performance differences between varchar and nvarchar SQL Server data types?
... AND ([URLa] IS NULL OR [URLu] IS NULL))
);
In this model you only SELECT from the [URL] computed column. For inserting and updating, you determine which field to use by seeing if converting alters the incoming value, which has to be of NVARCHAR type:
INSERT INTO TableName (..., URLa, URLu)...