大约有 47,000 项符合查询结果（耗时：0.0104秒） [XML]
Unable to cast object of type 'System.DBNull' to type 'System.String`
... even both. If the WHERE does not match any row, you'll get a null, if the selected row has NULL in that column, the return value is System.DBNull.
– Alexander
May 27 '14 at 7:52
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Convert timestamp to date in MySQL query
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SELECT * FROM users WHERE DATE_FORMAT(FROM_UNIXTIME(users.user_created_at),'%Y-%b-%e') = '2015-03-06' is this correct format or should i modify this?
– Dheeraj Thedijje
Mar 7 '18 at 11:4...
Truncate (not round) decimal places in SQL Server
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select round(123.456, 2, 1)
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In SQL, how can you “group by” in ranges?
...version.
Here are the correct versions of both of them on SQL Server 2000.
select t.range as [score range], count(*) as [number of occurences]
from (
select case
when score between 0 and 9 then ' 0- 9'
when score between 10 and 19 then '10-19'
else '20-99' end as range
from scores)...
How to return only the Date from a SQL Server DateTime datatype
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On SQL Server 2008 and higher, you should CONVERT to date:
SELECT CONVERT(date, getdate())
On older versions, you can do the following:
SELECT DATEADD(dd, 0, DATEDIFF(dd, 0, @your_date))
for example
SELECT DATEADD(dd, 0, DATEDIFF(dd, 0, GETDATE()))
gives me
2008-09-22 00:...
The cast to value type 'Int32' failed because the materialized value is null
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where u.ID == userID
select (int?)ch.Amount).Sum() ?? 0;
This first casts to int? to tell the C# compiler that this expression can indeed return null, even though Sum() returns an int. Then we use the normal ?? operator to handle the null case....
Check if value exists in Postgres array
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Simpler with the ANY construct:
SELECT value_variable = ANY ('{1,2,3}'::int[])
The right operand of ANY (between parentheses) can either be a set (result of a subquery, for instance) or an array. There are several ways to use it:
SQLAlchemy: how to filt...
How should I cast in VB.NET?
... Dim myList AS ArrayList=new ArrayList When you write (From e In myList select CType(e.Name,String)).ToArray() it doesn't work. I came to write ... select CType(e.Name.ToString,String)).ToArray() and I retrieved my smile.
– Bellash
Mar 25 '14 at 21:13
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LINQ query on a DataTable
...w in myDataTable.AsEnumerable()
where myRow.Field<int>("RowNo") == 1
select myRow;
And as @Keith says, you'll need to add a reference to System.Data.DataSetExtensions
AsEnumerable() returns IEnumerable<DataRow>. If you need to convert IEnumerable<DataRow> to a DataTable, use the...
Fastest way to determine if record exists
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SELECT TOP 1 products.id FROM products WHERE products.id = ?; will outperform all of your suggestions as it will terminate execution after it finds the first record.
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