大约有 47,000 项符合查询结果（耗时：0.0898秒） [XML]
How to select a single field for all documents in a MongoDB collection?
...nt such as:
db.student.find({}, {roll:1, _id:0})
The above statement will select all documents in the students collection, and the returned document will return only the roll field (and exclude the _id).
If we don't mention _id:0 the fields returned will be roll and _id. The '_id' field is always d...
MySQL Query to select data from last week?
Hi I have a table with a date field and some other information.
I want to select all entries from the past week, (week start from Sunday).
...
Datatype for storing ip address in SQL Server
...VARCHAR(15)) RETURNS BINARY(4)
AS
BEGIN
DECLARE @bin AS BINARY(4)
SELECT @bin = CAST( CAST( PARSENAME( @ip, 4 ) AS INTEGER) AS BINARY(1))
+ CAST( CAST( PARSENAME( @ip, 3 ) AS INTEGER) AS BINARY(1))
+ CAST( CAST( PARSENAME( @ip, 2 ) AS INTEGER) AS BINARY(1))
...
What is the simplest SQL Query to find the second largest value?
...
SELECT MAX( col )
FROM table
WHERE col < ( SELECT MAX( col )
FROM table )
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MySQL: selecting rows where a column is null
I'm having a problem where when I try to select the rows that have a NULL for a certain column, it returns an empty set. However, when I look at the table in phpMyAdmin, it says null for most of the rows.
...
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Oracle Differences between NVL and Coalesce
...the first non-NULL (there are some exceptions, such as sequence NEXTVAL):
SELECT SUM(val)
FROM (
SELECT NVL(1, LENGTH(RAWTOHEX(SYS_GUID()))) AS val
FROM dual
CONNECT BY
level <= 10000
)
This runs for almost 0.5 seconds, since it generates...
Difference between left join and right join in SQL Server [duplicate]
...
Select * from Table1 left join Table2 ...
and
Select * from Table2 right join Table1 ...
are indeed completely interchangeable. Try however Table2 left join Table1 (or its identical pair, Table1 right join Table2) to see...
How to set variable from a SQL query?
...
Using SELECT:
SELECT @ModelID = m.modelid
FROM MODELS m
WHERE m.areaid = 'South Coast'
Using SET:
SET @ModelID = (SELECT m.modelid
FROM MODELS m
WHERE m.areaid = 'South Coast')
See this...
How to set a selected option of a dropdown list control using angular JS
I am using Angular JS and I need to set a selected option of a dropdown list control using angular JS. Forgive me if this is ridiculous but I am new with Angular JS
...