大约有 45,000 项符合查询结果（耗时：0.0371秒） [XML]
Equivalent of LIMIT and OFFSET for SQL Server?
...nation it's better to write a query like this:
;WITH Results_CTE AS
(
SELECT
Col1, Col2, ...,
ROW_NUMBER() OVER (ORDER BY SortCol1, SortCol2, ...) AS RowNum
FROM Table
WHERE <whatever>
)
SELECT *
FROM Results_CTE
WHERE RowNum >= @Offset
AND RowNum < @Offset +...
How to check whether a file is empty or not?
... my_file.seek(0) #ensure you're at the start of the file..
... first_char = my_file.read(1) #get the first character
... if not first_char:
... print "file is empty" #first character is the empty string..
... else:
... my_file.seek(0) #first character wasn't empty, retu...
Generate a random number in the range 1 - 10
... 1 and 10 you mean any float that is >= 1 and < 10, then it's easy:
select random() * 9 + 1
This can be easily tested with:
# select min(i), max(i) from (
select random() * 9 + 1 as i from generate_series(1,1000000)
) q;
min | max
-----------------+------------------...
MySQL - UPDATE query based on SELECT Query
...can go here
ANSI SQL syntax:
UPDATE tableA SET validation_check =
(SELECT if(start_DTS > end_DTS, 'VALID', '') AS validation_check
FROM tableA
INNER JOIN tableB ON name_A = name_B
WHERE id_A = tableA.id_A)
Pick whichever one seems most natural to you.
...
How to get ID of the last updated row in MySQL?
...)
SET @update_id := 0;
UPDATE some_table SET column_name = 'value', id = (SELECT @update_id := id)
WHERE some_other_column = 'blah' LIMIT 1;
SELECT @update_id;
EDIT by aefxx
This technique can be further expanded to retrieve the ID of every row affected by an update statement:
SET @uids := nul...
Fastest check if row exists in PostgreSQL
...
Use the EXISTS key word for TRUE / FALSE return:
select exists(select 1 from contact where id=12)
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Check if table exists in SQL Server
...nge from version to version.
To check if a table exists use:
IF (EXISTS (SELECT *
FROM INFORMATION_SCHEMA.TABLES
WHERE TABLE_SCHEMA = 'TheSchema'
AND TABLE_NAME = 'TheTable'))
BEGIN
--Do Stuff
END
...
SQL RANK() versus ROW_NUMBER()
...he first 3 rows are tied when ordered by ID)
WITH T(StyleID, ID)
AS (SELECT 1,1 UNION ALL
SELECT 1,1 UNION ALL
SELECT 1,1 UNION ALL
SELECT 1,2)
SELECT *,
RANK() OVER(PARTITION BY StyleID ORDER BY ID) AS 'RANK',
ROW_NUMBER() OVER(PARTITION BY Style...
How do I provide custom cast support for my class?
... answered Sep 10 '09 at 21:12
Charles BretanaCharles Bretana
127k2222 gold badges136136 silver badges206206 bronze badges
...
How to declare a variable in MySQL?
...at has not been
initialized, it has a value of NULL and a type of string.
SELECT @var_any_var_name
You can initialize a variable using SET or SELECT statement:
SET @start = 1, @finish = 10;
or
SELECT @start := 1, @finish := 10;
SELECT * FROM places WHERE place BETWEEN @start AND @finish...