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Specifying column name in a “references” migration
I want to make a migration in Rails, referencing another table. Usually, I would do something like:
6 Answers
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How do I modify a MySQL column to allow NULL?
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You want the following:
ALTER TABLE mytable MODIFY mycolumn VARCHAR(255);
Columns are nullable by default. As long as the column is not declared UNIQUE or NOT NULL, there shouldn't be any problems.
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SQL - find records from one table which don't exist in another
I've got the following two SQL tables (in MySQL):
8 Answers
8
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Can you create nested WITH clauses for Common Table Expressions?
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While not strictly nested, you can use common table expressions to reuse previous queries in subsequent ones.
To do this, the form of the statement you are looking for would be
WITH x AS
(
SELECT * FROM MyTable
),
y AS
(
SELECT * FROM x
)
SELECT * FROM y
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Convert a list of data frames into one data frame
... but in about Sep 2011 a new function rbindlist was introduced in the data.table package version 1.8.2, with a remark that "This does the same as do.call("rbind",l), but much faster". How much faster?
library(rbenchmark)
benchmark(
do.call = do.call("rbind", listOfDataFrames),
plyr_rbind.fill ...
Most common way of writing a HTML table with vertical headers?
... option isn't quite valid HTML in the sense that all of the rows (TR) in a table should contain an equal number of columns (TD). Your header has 1 while the body has 3. You should use the colspan attribute to fix that.
Reference: "The THEAD, TFOOT, and TBODY sections must contain the same number of...
Android: upgrading DB version and adding new table
I've already created sqlite tables for my app, but now I want to add a new table to the database.
5 Answers
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How to Use slideDown (or show) function on a table row?
I'm trying to add a row to a table and have that row slide into view, however the slidedown function seems to be adding a display:block style to the table row which messes up the layout.
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HTML input textbox with a width of 100% overflows table cells
Does anyone know why the input elements with a width of 100% go over the table's cells border.
14 Answers
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Adding iOS UITableView HeaderView (not section header)
I want to add a table header (not section headers) like in the contacts app for example:
5 Answers
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