大约有 40,000 项符合查询结果（耗时：0.0171秒） [XML]
'IF' in 'SELECT' statement - choose output value based on column values
...
SELECT id,
IF(type = 'P', amount, amount * -1) as amount
FROM report
See http://dev.mysql.com/doc/refman/5.0/en/control-flow-functions.html.
Additionally, you could handle when the condition is null. In the case of...
How to declare a variable in a PostgreSQL query
...ows you to return a table of temporary values.
WITH master_user AS (
SELECT
login,
registration_date
FROM users
WHERE ...
)
SELECT *
FROM users
WHERE master_login = (SELECT login
FROM master_user)
AND (SELECT registration_date
FROM ma...
GROUP BY with MAX(DATE) [duplicate]
... to your group by clause, otherwise you need to rethink your query.
Try:
SELECT t.Train, t.Dest, r.MaxTime
FROM (
SELECT Train, MAX(Time) as MaxTime
FROM TrainTable
GROUP BY Train
) r
INNER JOIN TrainTable t
ON t.Train = r.Train AND t.Time = r.MaxTime
...
How to do INSERT into a table records extracted from another table
...UES", no parenthesis:
INSERT INTO Table2(LongIntColumn2, CurrencyColumn2)
SELECT LongIntColumn1, Avg(CurrencyColumn) as CurrencyColumn1 FROM Table1 GROUP BY LongIntColumn1;
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Entity Framework select distinct name
...
Using lambda expression..
var result = EFContext.TestAddresses.Select(m => m.Name).Distinct();
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How do you connect to multiple MySQL databases on a single webpage?
...d);
$dbh2 = mysql_connect($hostname, $username, $password, true);
mysql_select_db('database1', $dbh1);
mysql_select_db('database2', $dbh2);
Then to query database 1 pass the first link identifier:
mysql_query('select * from tablename', $dbh1);
and for database 2 pass the second:
mysql_query...
How do I check to see if a value is an integer in MySQL?
...e REGEXP operator, matching the string to a regular expression. Simply do
select field from table where field REGEXP '^-?[0-9]+$';
this is reasonably fast. If your field is numeric, just test for
ceil(field) = field
instead.
...
Paging with Oracle
... Say, if I pass 10 as a page number, and 120 as number of pages, from the select statement it would give me the 1880th through 1200th, or something like that, my math in my head might be off.
...
Using group by on multiple columns
..., to do with who is attending what subject at a university:
Table: Subject_Selection
+---------+----------+----------+
| Subject | Semester | Attendee |
+---------+----------+----------+
| ITB001 | 1 | John |
| ITB001 | 1 | Bob |
| ITB001 | 1 | Mickey |
| ITB001 ...
How to best display in Terminal a MySQL SELECT returning too many fields?
...
Terminate the query with \G in place of ;. For example:
SELECT * FROM sometable\G
This query displays the rows vertically, like this:
*************************** 1. row ***************************
Host: localhost
Db: mydatabase1
...