大约有 44,000 项符合查询结果（耗时：0.0433秒） [XML]
How do I perform the SQL Join equivalent in MongoDB?
...background as well, I would appreciate MongoDB taking a 'result set' (with selected returned fields) as input for a new query in one go, much like nested queries in SQL
– Stijn Sanders
Nov 26 '10 at 23:17
...
GROUP_CONCAT ORDER BY
...
You can use ORDER BY inside the GROUP_CONCAT function in this way:
SELECT li.client_id, group_concat(li.percentage ORDER BY li.views ASC) AS views,
group_concat(li.percentage ORDER BY li.percentage ASC)
FROM li GROUP BY client_id
...
MySQL和MongoDB设计实例进行对比 - 大数据 & AI - 清泛网 - 专注C/C++及内核技术
...并且外观设计是直板的手机，需按照如下方式查询：
SELECT * FROM `mobile_params` WHERE name = '待机时间' AND value > 100;
SELECT * FROM `mobile_params` WHERE name = '外观设计' AND value = '直板';
注：参数表为了方便，把数值和字符串统一保存成字...
Who architected / designed C++'s IOStreams, and would it still be considered well-designed by today'
...; operator will only read from the stream until it encounters a whitespace character, since there's no length information stored in the stream. So even though we output a string object containing "hello world", we're only going to input a string object containing "hello". So while the stream has s...
IN vs OR in the SQL WHERE Clause
...h are nearly instant. When the column is not indexed I got these results:
SELECT COUNT(*) FROM t_inner WHERE val IN (1000, 2000, 3000, 4000, 5000, 6000, 7000, 8000, 9000);
1 row fetched in 0.0032 (1.2679 seconds)
SELECT COUNT(*) FROM t_inner WHERE val = 1000 OR val = 2000 OR val = 3000 OR val = 40...
Why is iostream::eof inside a loop condition (i.e. `while (!stream.eof())`) considered wrong?
...ere's an extra \n at the end. I've covered this in another answer. Reading chars is a different matter because it only extracts one at a time and doesn't continue to hit the end.
– Joseph Mansfield
Apr 6 '13 at 16:59
...
How to select only the first rows for each unique value of a column
...
A very simple answer if you say you don't care which address is used.
SELECT
CName, MIN(AddressLine)
FROM
MyTable
GROUP BY
CName
If you want the first according to, say, an "inserted" column then it's a different query
SELECT
M.CName, M.AddressLine,
FROM
(
SELECT
...
Can we have multiple “WITH AS” in single sql - Oracle SQL
...
You can do this as:
WITH abc AS( select
FROM ...)
, XYZ AS(select
From abc ....) /*This one uses "abc" multiple times*/
Select
From XYZ.... /*using abc, XYZ multiple times*/
...
MySQL with Node.js
....log('connected as id ' + connection.threadId);
connection.query("select * from user",function(err,rows){
connection.release();
if(!err) {
res.json(rows);
}
});
connection.on('error', function(err) {
...
T-SQL get SELECTed value of stored procedure
...UTPUT parameter and a result set
ALSO, watch out if you use the pattern: SELECT @Variable=column FROM table ...
if there are multiple rows returned from the query, your @Variable will only contain the value from the last row returned by the query.
RETURN VALUE
since your query returns an int fie...