大约有 41,000 项符合查询结果（耗时：0.0302秒） [XML]
Store select query's output in one array in postgres
...
There are two ways. One is to aggregate:
SELECT array_agg(column_name::TEXT)
FROM information.schema.columns
WHERE table_name = 'aean'
The other is to use an array constructor:
SELECT ARRAY(
SELECT column_name
FROM information.schema.columns
WHERE table_name = ...
Why is 128==128 false but 127==127 is true when comparing Integer wrappers in Java?
...the JLS (5.1.7).
If the value p being boxed is true, false, a byte, a char in the range \u0000 to \u007f, or an int or short number between -128 and
127, then let r1 and r2 be the results of any two boxing conversions
of p. It is always the case that r1 == r2.
A simple rule to remember wh...
How to get ID of the last updated row in MySQL?
...)
SET @update_id := 0;
UPDATE some_table SET column_name = 'value', id = (SELECT @update_id := id)
WHERE some_other_column = 'blah' LIMIT 1;
SELECT @update_id;
EDIT by aefxx
This technique can be further expanded to retrieve the ID of every row affected by an update statement:
SET @uids := nul...
Is there a better way to dynamically build an SQL WHERE clause than by using 1=1 at its beginning?
... {2}", clause, appender, condition);
}
Use it like this
string query = "SELECT * FROM Table1 {0}";
string whereClause = string.Empty;
if (condition 1)
whereClause = AddCondition(whereClause, "AND", "Col=1");
if (condition 2)
whereClause = AddCondition(whereClause, "AND", "Col2=2");
str...
Only read selected columns
...from the data.table-package:
You can specify the desired columns with the select parameter from fread from the data.table package. You can specify the columns with a vector of column names or column numbers.
For the example dataset:
library(data.table)
dat <- fread("data.txt", select = c("Year...
how do I query sql for a latest record date for each user
...
select t.username, t.date, t.value
from MyTable t
inner join (
select username, max(date) as MaxDate
from MyTable
group by username
) tm on t.username = tm.username and t.date = tm.MaxDate
...
Max or Default?
...d, you can get around this limitation by casting to a nullable within your select. My VB is a little rusty, but I think it'd go something like this:
Dim x = (From y In context.MyTable _
Where y.MyField = value _
Select CType(y.MyCounter, Integer?)).Max
Or in C#:
var x = (from y...
Bootstrap datepicker hide after selection
How do I hide the calendar after a date is selected? Is there a specific function that I can use? My code below:
18 Answer...
What is the dual table in Oracle?
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It's a sort of dummy table with a single record used for selecting when you're not actually interested in the data, but instead want the results of some system function in a select statement:
e.g. select sysdate from dual;
See http://www.adp-gmbh.ch/ora/misc/dual.html
...
What is the correct file extension for GLSL shaders? [closed]
...haders.
You can store the vertex shader and fragment shader content in a char * variable and compile, link and attach the shader to a program.
Another way is to write the seperate vertex and fragment shader file with whatever extension you like and read it to compile, link and attach the shader t...