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How do I drop a foreign key constraint only if it exists in sql server?
...target a foreign key constraint on a specific table, use this:
IF EXISTS (SELECT *
FROM sys.foreign_keys
WHERE object_id = OBJECT_ID(N'dbo.FK_TableName_TableName2')
AND parent_object_id = OBJECT_ID(N'dbo.TableName')
)
ALTER TABLE [dbo.TableName] DROP CONSTRAINT [FK_TableName_TableName2]...
What is the lifetime of a static variable in a C++ function?
... emitter a("in if");
static emitter b("in foo");
}
int main(int argc, char*[])
{
foo(argc != 2);
if (argc == 3)
foo(false);
}
Output:
C:>sample.exe
Created in foo
Destroyed in foo
C:>sample.exe 1
Created in if
Created in foo
Destroyed in foo
Destroyed in if
C:>sample...
Python - Create a list with initial capacity
...iostream>
#include <chrono>
using namespace std;
void test(const char* name, void(*fn)(void))
{
cout << name << ": ";
auto start = chrono::high_resolution_clock::now();
for (unsigned int i = 0; i < Iterations; ++i) {
fn();
}
auto end = chrono::hi...
How do I URl encode something in Node.js?
...
You can use JavaScript's encodeURIComponent:
encodeURIComponent('select * from table where i()')
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jQuery empty() vs remove()
...
empty() will empty the selection of its contents, but preserve the selection itself.
remove() will empty the selection of its contents and remove the selection itself.
Consider:
<div>
<p><strong>foo</strong></p>
&...
data.table vs dplyr: can one do something well the other can't or does poorly?
... ## data.table syntax
left_join(DT2, DT1) ## dplyr syntax
# 2. select columns while join
DT1[DT2, .(z, i.mul)]
left_join(select(DT2, x, y, mul), select(DT1, x, y, z))
# 3. aggregate while join
DT1[DT2, .(sum(z) * i.mul), by = .EACHI]
DF1 %>% group_by(x, y) %>% summarise(z = su...
What's the difference between TRUNCATE and DELETE in SQL
...tranTest | DELETE FROM tranTest |
| SELECT * FROM tranTest | SELECT * FROM tranTest |
| ROLLBACK | ROLLBACK |
| SELECT * FROM tranTest | SELE...
Table Naming Dilemma: Singular vs. Plural Names [closed]
...
Customer
Customer.CustomerID
CustomerAddress
public Class Customer {...}
SELECT FROM Customer WHERE CustomerID = 100
Once you know you are dealing with "Customer", you can be sure you will use the same word for all of your database interaction needs.
Reason 5. (Globalization). The world is gettin...
Asp.net - Add blank item at top of dropdownlist
...drpList.Items.Insert(0, new ListItem(String.Empty, String.Empty));
drpList.SelectedIndex = 0;
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SQLite 数据库使用指导 · App Inventor 2 中文网
...消息 }
procedure 刷新列表() {
列表显示框1.Elements = SQLite1.SelectSQL("SELECT content FROM notes ORDER BY id DESC", list())
}
运行效果：输入文字点「添加」，最新一条出现在列表顶部；退出应用再打开，记录仍在。
要点：
必须先打开数...