大约有 40,000 项符合查询结果（耗时：0.0305秒） [XML]
LINQ to SQL Left Outer Join
...table), where-as yours matches only 0-1. To do a left outer join, you need SelectMany and DefaultIfEmpty, for example:
var query = from c in db.Customers
join o in db.Orders
on c.CustomerID equals o.CustomerID into sr
from x in sr.DefaultIfEmpty()
s...
Why do we always prefer using parameters in SQL statements?
I am very new to working with databases. Now I can write SELECT , UPDATE , DELETE , and INSERT commands. But I have seen many forums where we prefer to write:
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How to save MySQL query output to excel or .txt file? [duplicate]
...SV file:
MySQL provides an easy mechanism for writing the results of a select
statement into a text file on the server. Using extended options of
the INTO OUTFILE nomenclature, it is possible to create a comma
separated value (CSV) which can be imported into a spreadsheet
application suc...
MySQL SELECT WHERE datetime matches day (and not necessarily time)
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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...
NULL values inside NOT IN clause
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Query A is the same as:
select 'true' where 3 = 1 or 3 = 2 or 3 = 3 or 3 = null
Since 3 = 3 is true, you get a result.
Query B is the same as:
select 'true' where 3 <> 1 and 3 <> 2 and 3 <> null
When ansi_nulls is on, 3 <&...
Get records with max value for each group of grouped SQL results
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There's a super-simple way to do this in mysql:
select *
from (select * from mytable order by `Group`, age desc, Person) x
group by `Group`
This works because in mysql you're allowed to not aggregate non-group-by columns, in which case mysql just returns the first row. T...
Get contentEditable caret index position
...tion(editableDiv) {
var caretPos = 0,
sel, range;
if (window.getSelection) {
sel = window.getSelection();
if (sel.rangeCount) {
range = sel.getRangeAt(0);
if (range.commonAncestorContainer.parentNode == editableDiv) {
caretPos = range.endOffset;
}
...
Datetime equal or greater than today in MySQL
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SELECT * FROM users WHERE created >= CURDATE();
But I think you mean created < today
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MySQL case insensitive select
Can anyone tell me if a MySQL SELECT query is case sensitive or case insensitive by default? And if not, what query would I have to send so that I can do something like:
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“where 1=1” statement [duplicate]
...hould ignore it
No magic, just practical
Example Code:
commandText = "select * from car_table where 1=1";
if (modelYear <> 0) commandText += " and year="+modelYear
if (manufacturer <> "") commandText += " and value="+QuotedStr(manufacturer)
if (color <> "") command...