大约有 5,880 项符合查询结果（耗时：0.0325秒） [XML]
Using group by on multiple columns
...one group.
To illustrate using an example, let's say we have the following table, to do with who is attending what subject at a university:
Table: Subject_Selection
+---------+----------+----------+
| Subject | Semester | Attendee |
+---------+----------+----------+
| ITB001 | 1 | John ...
Why is the tag deprecated in HTML?
...nvas. It is only deprecated because of the war against marquees, centers, tables, frame which is purely religious, as they all have a place.
– Dmitry
Jun 5 '16 at 18:23
...
Update or Insert (multiple rows and columns) from subquery in PostgreSQL
...
For the UPDATE
Use:
UPDATE table1
SET col1 = othertable.col2,
col2 = othertable.col3
FROM othertable
WHERE othertable.col1 = 123;
For the INSERT
Use:
INSERT INTO table1 (col1, col2)
SELECT col1, col2
FROM othertable
You don't ...
Expand div to max width when float:left is set
...
The best way is to use a simple 2 cols table instead of wasting time adding tons of CSS not-cross-browser-compatibles tricks
– Marco Demaio
Nov 23 '12 at 10:22
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How do exceptions work (behind the scenes) in c++
...atching_functionv, .-_Z20my_catching_functionv
.section .gcc_except_table,"a",@progbits
.align 4
.LLSDA9:
.byte 0xff
.byte 0x0
.uleb128 .LLSDATT9-.LLSDATTD9
.LLSDATTD9:
.byte 0x1
.uleb128 .LLSDACSE9-.LLSDACSB9
.LLSDACSB9:
.uleb128 .LEHB0-.LFB9
.uleb128 .L...
Nginx缓存解决方案：SRCache - 更多技术 - 清泛网 - 专注C/C++及内核技术
...request_uri_without_args = ngx.re.sub(ngx.var.request_uri, "\\?.*", "")
table.unpack = table.unpack or unpack
for index, rule in ipairs(phoenix["rule"]) do
if type(rule["regex"]) == "string" then
rule["regex"] = {rule["regex"], ""}
end
local regex, options = table.unp...
Rails auto-assigning id that already exists
...to set the sequence for your company.id column to the highest value in the table with a query like this:
SELECT setval('company_id_seq', (SELECT max(id) FROM company));
I am guessing at your sequence name "company_id_seq", table name "company", and column name "id" ... please replace them with th...
Opposite of %in%: exclude rows with values specified in a vector
...
If you look at the code of %in%
function (x, table) match(x, table, nomatch = 0L) > 0L
then you should be able to write your version of opposite. I use
`%not in%` <- function (x, table) is.na(match(x, table, nomatch=NA_integer_))
Another way is:
function (x,...
Strings as Primary Keys in SQL Database [closed]
... key then you should probably use it. This all depends on the size of the table you're making it for and the length of the string that is going to be the primary key (longer strings == harder to compare). I wouldn't necessarily use a string for a table that has millions of rows, but the amount of p...
搭建高可用mongodb集群（四）—— 分片 - 大数据 & AI - 清泛网 - 专注C/C++及内核技术
...需要分片的集合和片键
db.runCommand( { shardcollection : "testdb.table1",key : {id: 1} } )
我们设置testdb的 table1 表需要分片，根据 id 自动分片到 shard1 ，shard2，shard3 上面去。要这样设置是因为不是所有mongodb 的数据库和表 都需要分片！
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