大约有 40,000 项符合查询结果（耗时：0.0580秒） [XML]
Postgres: Distinct but only for one column
I have a table on pgsql with names (having more than 1 mio. rows), but I have also many duplicates. I select 3 fields: id , name , metadata .
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Understanding :source option of has_one/has_many through of Rails
...ular, to represent the model name, instead of :breeds which represents the table name? E.g. has_many :dog_breeds, :through => :dogs, :source => :breed (no s suffixing :breed)?
– LazerSharks
Dec 30 '14 at 22:22
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Effect of a Bitwise Operator on a Boolean in Java
...| have different precedence from & and |.
Extract from the precedence table (with highest precedence at the top).
bitwise AND &
bitwise exclusive OR ^
bitwise inclusive OR |
logical AND &&
logical OR ||
What this mean...
Why C# implements methods as non-virtual by default?
...erformance concern because every method call must use the object's Virtual Table. Moreover, this strongly limits the Just-In-Time compiler's ability to inline methods and perform other kinds of optimization.
3- Most importantly, if methods are not virtual by default, you can guarantee the behavior ...
SQL is null and = null [duplicate]
...showing a variety of conditions and and their effect as per above.
create table t (x int, y int);
insert into t values (null, null), (null, 1), (1, 1);
select 'x = null' as test , x, y from t where x = null
union all
select 'x != null', x, y from t where x != null
union all
select 'not (x = null)'...
How to pass anonymous types as parameters?
...ruct Data {
public string ColumnName;
}
var query = (from name in some.Table
select new Data { ColumnName = name });
MethodOp(query);
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MethodOp(IEnumerable<Data> enumerable);
In this case though, you are only selecting a single field, so it may be easier to just select the ...
Oracle SQL escape character (for a '&')
...t the define character to something other than &
SET DEFINE ~
create table blah (x varchar(20));
insert into blah (x) values ('blah&amp');
select * from blah;
X
--------------------
blah&amp
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How can I stop float left?
...iv>.
Then add this CCS:
.row::after {content: ""; clear: both; display: table;}
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How to convert int to char with leading zeros?
...])) * (1+SIGN(@DesiredLenght-LEN([Column])) / 2) ),
[Column])
FROM Table;
Multiplication by SIGN expression is equivalent to MAX(0, @DesiredLenght-LEN([Column])). The problem is that MAX() accepts only one argument...
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Rails select helper - Default selected value, how?
...ue, and once I populated my @project variable with an id from the database table, instead of a title, this code worked appended onto the back of the form.select helper: selected: @project Thank you @danengle
– Christopher Warrington
Jan 27 '18 at 22:17
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