大约有 43,000 项符合查询结果（耗时：0.0098秒） [XML]
MySQL SELECT WHERE datetime matches day (and not necessarily time)
...
NEVER EVER use a selector like DATE(datecolumns) = '2012-12-24' - it is a performance killer:
it will calculate DATE() for all rows, including those, that don't match
it will make it impossible to use an index for the query
It is much fas...
Increment value in mysql update query
...ion to numbers.
To demonstrate, the following will produce the result 6:
SELECT ' 05.05 '+'.95';
String concatenation in MySQL requires the CONCAT() function so there is no ambiguity here and MySQL converts the strings to floats and adds them together.
I actually think the reason the initial q...
Why does integer division in C# return an integer and not a float?
...ation of the form x / y, binary operator overload resolution is applied to select a specific operator implementation. The operands are converted to the parameter types of the selected operator, and the type of the result is the return type of the operator.
The predefined division operators are ...
Detect if value is number in MySQL
...
This should work in most cases.
SELECT * FROM myTable WHERE concat('',col1 * 1) = col1
It doesn't work for non-standard numbers like
1e4
1.2e5
123. (trailing decimal)
share
...
C# Interfaces. Implicit implementation versus Explicit implementation
...t interested in populating the list; instead, they just want to be able to select a customer by GUID or to obtain the selected customer's GUID. A presenter would populate the box on the first page load, and this presenter is encapsulated by the control.
public sealed class CustomerComboBox : ComboBo...
How to export all data from table to an insertable sql format?
... top level of the context menu Thanks to Daniel for the comment to update.
Select generate scripts
Click next
Choose tables
Click next
Click advanced
Scroll to Types of data to script - Called types of data to script in SMSS 2014 Thanks to Ellesedil for commenting
Select data only
Click on 'Ok' to c...
Why does an NSInteger variable have to be cast to long when used as a format argument?
...
I suppose the selected answer is technically the best answer to the question, but if you want to know how to avoid casting each occurrence and prevent warnings then I find this is the best solution.
– Daniel Wood
...
Concatenate multiple result rows of one column into one, group by another column [duplicate]
...Simpler with the aggregate function string_agg() (Postgres 9.0 or later):
SELECT movie, string_agg(actor, ', ') AS actor_list
FROM tbl
GROUP BY 1;
The 1 in GROUP BY 1 is a positional reference and a shortcut for GROUP BY movie in this case.
string_agg() expects data type text as input. Other ...
Generate MD5 hash string with T-SQL
...
Use HashBytes
SELECT HashBytes('MD5', 'email@dot.com')
That will give you 0xF53BD08920E5D25809DF2563EF9C52B6
-
SELECT CONVERT(NVARCHAR(32),HashBytes('MD5', 'email@dot.com'),2)
That will give you F53BD08920E5D25809DF2563EF9C52B6
...
SQL query to get all values a enum can have
...
If you want an array:
SELECT enum_range(NULL::myenum)
If you want a separate record for each item in the enum:
SELECT unnest(enum_range(NULL::myenum))
Additional Information
This solution works as expected even if your enum is not in the...