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How to update column with null value
... your column cannot be null, when you set the value to null it will be the cast value to it.
Here a example
mysql> create table example ( age int not null, name varchar(100) not null );
mysql> insert into example values ( null, "without num" ), ( 2 , null );
mysql> select * from example;
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How to convert DateTime? to DateTime
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You can use a simple cast:
DateTime dtValue = (DateTime) dtNullAbleSource;
As Leandro Tupone said, you have to check if the var is null before
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mfc spin control 用法 - C/C++ - 清泛网 - 专注C/C++及内核技术
... *pNMHDR, LRESULT *pResult)
{
LPNMUPDOWN pNMUpDown = reinterpret_cast<LPNMUPDOWN>(pNMHDR);
// TODO: 在此添加控件通知处理程序代码
if(pNMUpDown->iDelta == 1) // 如果此值为1 , 说明点击了Spin的往下箭头
{...
}
el...
CListCtrl 点击/双击怎么样获得行号，列号 - C/C++ - 清泛网 - 专注C/C++及内核技术
...st(NMHDR* pNMHDR, LRESULT* pResult)
{
LPNMLISTVIEW pNMLV = reinterpret_cast<LPNMLISTVIEW>(pNMHDR);
int row = pNMLV->iItem;
int col = pNMLV->iSubItem;
CString str;
str.Format("行号：%d, 列号：%d", row, col);
AfxMessageBox(str);
}
CListCtrl 行号 列号
mfc spin control 用法 - C++ UI - 清泛IT社区，为创新赋能！
...{
LPNMUPDOWN pNMUpDown = reinterpret_cast<LPNMUPDOWN>(pNMHDR);
// TODO: 在此添加控件通知处理程序代码
if(pNMUpDown->iDelta == 1) &nb...
Is there a conditional ternary operator in VB.NET?
...e types - see this answer as to why and this answer for a workaround which casts the argument before returning (CType(Nothing, DateTime?).
– KyleMit
Jan 17 '17 at 19:31
add a ...
const char* concatenation
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@luiscubal: Yes that would work too...just use a (char*) cast, as calloc returns void*
– codaddict
Jan 3 '10 at 14:31
5
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Convert string[] to int[] in one line of code using LINQ
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you can simply cast a string array to int array by:
var converted = arr.Select(int.Parse)
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ArrayIndexOutOfBoundsException when using the ArrayList's iterator
...Next();) {
x = iterator.next();
//do some stuff
}
Its a good practice to cast and use the object.
For example, if the 'arrayList' contains a list of 'Object1' objects. Then, we can re-write the code as:
for(Iterator iterator = arrayList.iterator(); iterator.hasNext();) {
x = (Object1) iterator.ne...
View array in Visual Studio debugger? [duplicate]
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Note that you can also use a cast in the debug view. If pArray is of type void* you can type (char*) pArray, 10 which will display the content of the array interpreted as char.
– VoidStar
Aug 15 '13 at 9:26
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