大约有 30,000 项符合查询结果（耗时：0.0231秒） [XML]
How do I (or can I) SELECT DISTINCT on multiple columns?
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SELECT DISTINCT a,b,c FROM t
is roughly equivalent to:
SELECT a,b,c FROM t GROUP BY a,b,c
It's a good idea to get used to the GROUP BY syntax, as it's more powerful.
For your query, I'd do it like this:
UPDATE sale...
Install Node.js on Ubuntu
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wget -qO- https://raw.githubusercontent.com/creationix/nvm/v0.19.0/install.sh | bash
nvm install v0.10.33
just use nvm for node version control nvm
share
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Delete duplicate rows from small table
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DELETE FROM dupes a
WHERE a.ctid <> (SELECT min(b.ctid)
FROM dupes b
WHERE a.key = b.key);
share
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improve this answer
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How to reset sequence in postgres and fill id column with new data?
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SELECT setval('seq', 1, FALSE) should do the same (here, the third argument, FALSE, does the magic, as it shows that nextval must be 1 instead of 2)
– Vasilen Donchev
Sep 22 '15 at 14:43...
Why does Windows64 use a different calling convention from all other OSes on x86-64?
... RAX (return value) and RCX, RDX, R8, R9 (arg[0..3]) are an understandable selection if you choose four registers for arguments.
I don't know why the AMD64 UN*X ABI chose RDX before RCX.
Choosing six argument registers on x64 - UN*X specific
UN*X, on RISC architectures, has traditionally done argume...
MySQL get row position in ORDER BY
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Use this:
SELECT x.id,
x.position,
x.name
FROM (SELECT t.id,
t.name,
@rownum := @rownum + 1 AS position
FROM TABLE t
JOIN (SELECT @rownum := 0) r
ORDER BY t.name)...
Generate GUID in MySQL for existing Data?
...e BEFORE UPDATE on YourTable
FOR EACH ROW
BEGIN
SET new.guid_column := (SELECT UUID());
END
//
Then execute
UPDATE YourTable set guid_column = (SELECT UUID());
And DROP TRIGGER beforeYourTableUpdate;
UPDATE
Another solution that doesn't use triggers, but requires primary key or unique inde...
Do htmlspecialchars and mysql_real_escape_string keep my PHP code safe from injection?
...nerable to certain attack vectors.
Imagine the following SQL:
$result = "SELECT fields FROM table WHERE id = ".mysql_real_escape_string($_POST['id']);
You should be able to see that this is vulnerable to exploit.
Imagine the id parameter contained the common attack vector:
1 OR 1=1
There's no...
How to fetch the row count for all tables in a SQL SERVER database [duplicate]
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EXEC sp_MSForEachTable @command1='INSERT #counts (table_name, row_count) SELECT ''?'', COUNT(*) FROM ?'
SELECT table_name, row_count FROM #counts ORDER BY table_name, row_count DESC
DROP TABLE #counts
The output will be a list of tables and their row counts.
If you just want the total row count...
How to drop column with constraint?
...ing of constraints script:
DECLARE @sql NVARCHAR(MAX)
WHILE 1=1
BEGIN
SELECT TOP 1 @sql = N'alter table tbloffers drop constraint ['+dc.NAME+N']'
from sys.default_constraints dc
JOIN sys.columns c
ON c.default_object_id = dc.object_id
WHERE
dc.parent_object_id = OBJ...