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When to use Common Table Expression (CTE)
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Interesting fact about CTE. I always wondered why NEWID() in the CTE changes when the CTE is referenced more than once. select top 100 * into #tmp from master..spt_values order by 1,2,3,4 select A.number, COUNT(*) from #tmp A inner join #tmp B ON A.number = B.number+1 group by...
Delete sql rows where IDs do not have a match from another table
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Using LEFT JOIN/IS NULL:
DELETE b FROM BLOB b
LEFT JOIN FILES f ON f.id = b.fileid
WHERE f.id IS NULL
Using NOT EXISTS:
DELETE FROM BLOB
WHERE NOT EXISTS(SELECT NULL
FROM FILES f
WHERE f.id = fileid)
Using NOT IN:
DELETE FROM BLOB
WHERE fi...
SQL Server add auto increment primary key to existing table
...ting table which is already populated with 150000 records. I have added an Id column (which is currently null).
15 Answers
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How do I get a list of all the duplicate items using pandas in python?
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Method #1: print all rows where the ID is one of the IDs in duplicated:
>>> import pandas as pd
>>> df = pd.read_csv("dup.csv")
>>> ids = df["ID"]
>>> df[ids.isin(ids[ids.duplicated()])].sort("ID")
ID ENROLLMENT_DATE ...
SQL Server query to find all permissions/access for all users in a database
...at a query, based on Andomar's suggestions. This query is intended to provide a list of permissions that a user has either applied directly to the user account, or through
roles that the user has.
/*
Security Audit Report
1) List all access provisioned to a sql user or windows user/group directly ...
Rails: Using greater than/less than with a where statement
I'm trying to find all Users with an id greater than 200, but I'm having some trouble with the specific syntax.
9 Answers
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Linq code to select one item
...use the extension methods directly like:
var item = Items.First(i => i.Id == 123);
And if you don't want to throw an error if the list is empty, use FirstOrDefault which returns the default value for the element type (null for reference types):
var item = Items.FirstOrDefault(i => i.Id == ...
How to annotate MYSQL autoincrement field with JPA annotations
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To use a MySQL AUTO_INCREMENT column, you are supposed to use an IDENTITY strategy:
@Id @GeneratedValue(strategy=GenerationType.IDENTITY)
private Long id;
Which is what you'd get when using AUTO with MySQL:
@Id @GeneratedValue(strategy=GenerationType.AUTO)
private Long id;
Which is a...
Jquery If radio button is checked
I have these 2 radio buttons at the moment so that the user can decide whether they need postage included in the price or not:
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What is the standard naming convention for html/css ids and classes?
...sing it a lot. For example, if you've got your underscore key on the underside of the keyboard (unlikely, but entirely possible), then stick to hyphens. Just go with what is best for yourself. Additionally, all 3 of these conventions are easily readable. If you're working in a team, remember to keep...