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莱昂氏unix源代码分析 PDF - 文档下载 - 清泛网 - 专注C/C++及内核技术
...本书适合UNIX操作系统编程人员、大专院校师生学习参考使用。
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序(一)
序(二)
历史注记
上篇 UNIX操作系统版本6源代码
UNIX操作系统过程分类索引 3
UNIX操作系统文件及过程 5
UNIX操作系统定义的符号...
List of foreign keys and the tables they reference
...en incredibly handy.
Save it off so you can execute it directly (@fkeys.sql). It will let you search by Owner and either the Parent or Child table and show foreign key relationships. The current script does explicitly spool to C:\SQLRPTS so you will need to create that folder of change that lin...
Delete all Duplicate Rows except for One in MySQL? [duplicate]
How would I delete all duplicate data from a MySQL Table?
2 Answers
2
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MySQL Multiple Joins in one query?
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I shared my experience of using two LEFT JOINS in a single SQL query.
I have 3 tables:
Table 1) Patient consists columns PatientID, PatientName
Table 2) Appointment consists columns AppointmentID, AppointmentDateTime, PatientID, DoctorID
Table 3) Doctor consists columns DoctorID,...
ALTER TABLE without locking the table?
When doing an ALTER TABLE statement in MySQL, the whole table is read-locked (allowing concurrent reads, but prohibiting concurrent writes) for the duration of the statement. If it's a big table, INSERT or UPDATE statements could be blocked for a looooong time. Is there a way to do a "hot alter", li...
SQLite - How do you join tables from different databases?
I have an application that uses a SQLite database and everything works the way it should. I'm now in the process of adding new functionalities that require a second SQLite database, but I'm having a hard time figuring out how to join tables from the different databases.
...
Django in / not in query
...ite to exact. Author.objects.filter(name__ne='Jack') will translate to the SQL: "author"."name" <> 'Jack'"
from django.db.models import Lookup
class NotEqual(Lookup):
lookup_name = 'ne'
def as_sql(self, compiler, connection):
lhs, lhs_params = self.process_lhs(compiler, conn...
How to find gaps in sequential numbering in mysql?
...ve, syntax can be generated for other programming languages. Or maybe even SQL.
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string.ToLower() and string.ToLowerInvariant()
... in Turkey.
=Using ToLower incorrectly=
Now pretend you are writing an SQL parser. Somewhere you will have code that looks like:
if(operator.ToLower() == "like")
{
// Handle an SQL LIKE operator
}
The SQL grammar does not change when you change cultures. A Frenchman does not write SÉLECT...
Compare two data.frames to find the rows in data.frame 1 that are not present in data.frame 2
...
SQLDF provides a nice solution
a1 <- data.frame(a = 1:5, b=letters[1:5])
a2 <- data.frame(a = 1:3, b=letters[1:3])
require(sqldf)
a1NotIna2 <- sqldf('SELECT * FROM a1 EXCEPT SELECT * FROM a2')
And the rows which...