大约有 37,000 项符合查询结果（耗时：0.0206秒） [XML]
The multi-part identifier could not be bound
...
FROM (a, b) LEFT JOIN dkcd ON …
WHERE …
that is, the combination of tables a and b is joined with the table dkcd. In fact, what's happening is
SELECT
…
FROM a, (b LEFT JOIN dkcd ON …)
WHERE …
that is, as you may already have understood, dkcd is joined specifically against b and onl...
Change a column type from Date to DateTime during ROR migration
...
First in your terminal:
rails g migration change_date_format_in_my_table
Then in your migration file:
For Rails >= 3.2:
class ChangeDateFormatInMyTable < ActiveRecord::Migration
def up
change_column :my_table, :my_column, :datetime
end
def down
change_column :my_tabl...
Compare two MySQL databases [closed]
... sets, etc. mysqldump --opt --compact --skip-extended-insert -u user -p db table > file.sql
– zanlok
Mar 6 '12 at 21:53
...
Parse JSON in TSQL
...le Talk website that outlines how to take a JSon string and output it into tables and columns that can be queried. This is for SQL Server 2016: https://www.simple-talk.com/sql/learn-sql-server/json-support-in-sql-server-2016/
– codeaf
Jul 28 '16 at 18:10
...
Check if value exists in Postgres array
...
how can I search for a column from another table to have a value in the array? e.g. select * from beers where style_id in (select preferences from users where id=1) limit 1; style_id is an integer data type; preferences is integer[] I get this error ERROR: operato...
How to drop columns using Rails migration
What's the syntax for dropping a database table column through a Rails migration?
20 Answers
...
Is there any performance gain in indexing a boolean field?
...is is not entirely correct, without an index mySql needs to scan the whole table to find the relevant rows.
– ilanco
May 9 '12 at 22:04
4
...
How to customize the background color of a UITableViewCell?
...ike to customize the background (and maybe the border too) of all of the UITableViewCells within my UITableView. So far I have not been able to customize this stuff, so I have a bunch of white background cells which is the default.
...
Remove specific characters from a string in Python
...
Strings in Python are immutable (can't be changed). Because of this, the effect of line.replace(...) is just to create a new string, rather than changing the old one. You need to rebind (assign) it to line in order to have that variable take the new...
Is there a way to get a collection of all the Models in your Rails app?
...
ActiveRecord::Base.connection.tables.map do |model|
model.capitalize.singularize.camelize
end
will return
["Article", "MenuItem", "Post", "ZebraStripePerson"]
Additional information If you want to call a method on the object name without model:stri...