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explicit casting from super class to subclass
...does not generate a compilation error, but at runtime it generates a ClassCastException . Why can't the compiler detect this error?
...
What is an “unwrapped value” in Swift?
...gift:getGift())
//Now we have to unwrap f00, unwrap its entry, then force cast it into the type we hope it is, and then repeat this in nested fashion until we get to the final value.
var b4r = (((((((((((f00![10]! as! [Int:Any?])[9]! as! [Int:Any?])[8]! as! [Int:Any?])[7]! as! [Int:Any?])[6]! as! ...
What is the difference between ExecuteScalar, ExecuteReader and ExecuteNonQuery?
... then the result is the first column of 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...
generate days from date range
...000 days, and could be extended to go as far back or forward as you wish.
select a.Date
from (
select curdate() - INTERVAL (a.a + (10 * b.a) + (100 * c.a) + (1000 * d.a) ) DAY as Date
from (select 0 as a union all select 1 union all select 2 union all select 3 union all select 4 union all ...
How can I convert a std::string to int?
...stinguish between bad input (see here).
4. Fourth option: Boost's lexical_cast
#include <boost/lexical_cast.hpp>
#include <string>
std::string str;
try {
int i = boost::lexical_cast<int>( str.c_str());
float f = boost::lexical_cas...
How can I check if a View exists in a Database?
...
FOR SQL SERVER
IF EXISTS(select * FROM sys.views where name = '')
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Assign null to a SqlParameter
...value or a DBNull type value, which are not compatible.
You can of course cast the instance of AgeIndex to be type object which would satisfy the ?: requirement.
You can use the ?? null-coalescing operator as follows
SqlParameter[] parameters = new SqlParameter[1];
SqlParameter planIndexPara...
SQL WHERE.. IN clause multiple columns
...a derived table from the subquery, and join table1 to this derived table:
select * from table1 LEFT JOIN
(
Select CM_PLAN_ID, Individual_ID
From CRM_VCM_CURRENT_LEAD_STATUS
Where Lead_Key = :_Lead_Key
) table2
ON
table1.CM_PLAN_ID=table2.CM_PLAN_ID
AND table1.Individual=table2.Indi...
Converting bool to text in C++
...Boost that can help us out here. Boost has a nice function called lexical_cast. We can use it thus:
boost::lexical_cast<std::string>(my_bool)
Now, it's true to say that this is higher overhead than some macro; stringstreams deal with locales which you might not care about, and create a dy...
How can I cast int to enum?
How can an int be cast to an enum in C#?
31 Answers
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