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Best practices for SQL varchar column length [closed]
Every time is set up a new SQL table or add a new varchar column to an existing table, I am wondering one thing: what is the best value for the length .
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How to convert a column number (e.g. 127) into an Excel column (e.g. AA)
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Here's how I do it:
private string GetExcelColumnName(int columnNumber)
{
int dividend = columnNumber;
string columnName = String.Empty;
int modulo;
while (dividend > 0)
{
modulo = (dividend - 1) % 26;
columnName ...
How important is the order of columns in indexes?
...mns involved.
Giving that rationale, the only difference is comparing two 'strings' that differ earlier versus later in the string. This is a tiny part of the total cost. There is no "first pass / second pass", as mentioned in one Answer.
So, what order should be used?
Start with column(s) tested...
How to find all serial devices (ttyS, ttyUSB, ..) on Linux without opening them?
...s.h>
#include <sys/stat.h>
#include <unistd.h>
#include <string.h>
#include <fcntl.h>
#include <termios.h>
#include <sys/ioctl.h>
#include <linux/serial.h>
#include <iostream>
#include <list>
using namespace std;
static string get_driver(co...
PostgreSQL Crosstab Query
... the provided input query: row_name, category, value. There is no room for extra columns like in the 2-parameter alternative below.
Safe form
crosstab(text, text) with 2 input parameters:
SELECT *
FROM crosstab(
'SELECT section, status, ct
FROM tbl
ORDER BY 1,2' -- could also ju...
Turn a simple socket into an SSL socket
...ill need to initialize OpenSSL:
void InitializeSSL()
{
SSL_load_error_strings();
SSL_library_init();
OpenSSL_add_all_algorithms();
}
void DestroySSL()
{
ERR_free_strings();
EVP_cleanup();
}
void ShutdownSSL()
{
SSL_shutdown(cSSL);
SSL_free(cSSL);
}
Now for the bulk o...
How to check whether a string contains a substring in JavaScript?
Usually I would expect a String.contains() method, but there doesn't seem to be one.
3 Answers
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const char *, char const *, char * const 异同？const修饰符各位置有何区...
const char *, char const *, char * const 异同？const修饰符各位置有何区别？const char * p = new char('a'); 这个是常字符，即p的内容不能被修改。char const * p 意义同上，没有区别。 这时，*...const char * p = new char('a'); 这个是常字符，即p的内容...
How to read a CSV file into a .NET Datatable
...m.Globalization;
// using System.IO;
static DataTable GetDataTableFromCsv(string path, bool isFirstRowHeader)
{
string header = isFirstRowHeader ? "Yes" : "No";
string pathOnly = Path.GetDirectoryName(path);
string fileName = Path.GetFileName(path);
string sql = @"SELECT * FROM ["...
C read file line by line
... printf(line) is wrong! Do not do this. This opens your code to a string format vulnerability where you can freely read/write directly to memory via the stuff being printed. If I were to put %n/%p in the file and point the pointer back to an address in memory (in the string from the file) t...