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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...
MySQL Multiple Joins in one query?
...
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.
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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
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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...
PHP - Modify current object in foreach loop
...logic.
For retrieving objects by ID / PK, depending upon if you are using SQL or not (it seems suggested), I'd use a filter to ensure I get an array of valid PK's, then implode with comma and place into an SQL IN() clause to return the result-set. It makes one call instead of several via SQL, optim...
30条爆笑的程序员梗 PHP是最好的语言 - 轻松一刻 - 清泛网 - 专注C/C++及内核技术
...公路下山时坏在半路上了。于是两位工程师和一位经理就如何修车的问题 展开了讨论。
硬件工程师说：“我可以用随身携带的瑞士军刀把车坏的部分拆下来，找出原因，排除故障。”
项目经理说：“根据经营管理学，应该召...