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Fastest way to replace NAs in a large data.table
I have a large data.table , with many missing values scattered throughout its ~200k rows and 200 columns. I would like to re code those NA values to zeros as efficiently as possible.
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Copy rows from one Datatable to another DataTable?
How can I copy specific rows from DataTable to another Datable in c#? There will be more than one row.
11 Answers
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How do I drop a foreign key constraint only if it exists in sql server?
I can drop a table if it exists using the following code but do not know how to do the same with a constraint:
10 Answers
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jquery UI Sortable with table and tr width
I am using jQuery UI sortable to make my table grid sortable. The code seems to work fine but because I am not adding width to td s, when I drag the tr it shrinks the content.
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Add a column to a table, if it does not already exist
I want to write a query for MS SQL Server that adds a column into a table. But I don't want any error display, when I run/execute the following query.
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How do I find a “gap” in running counter with SQL?
I'd like to find the first "gap" in a counter column in an SQL table. For example, if there are values 1,2,4 and 5 I'd like to find out 3.
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Rails has_and_belongs_to_many migration
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You need to add a separate join table with only a restaurant_id and user_id (no primary key), in alphabetical order.
First run your migrations, then edit the generated migration file.
Rails 3
rails g migration create_restaurants_users_table
Rails 4:
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Return number of rows affected by UPDATE statements
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CREATE PROCEDURE UpdateTables
AS
BEGIN
-- SET NOCOUNT ON added to prevent extra result sets from
-- interfering with SELECT statements.
SET NOCOUNT ON;
DECLARE @RowCount1 INTEGER
DECLARE @RowCount2 INTEGER
DECLARE @RowCount3...
List columns with indexes in PostgreSQL
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Create some test data...
create table test (a int, b int, c int, constraint pk_test primary key(a, b));
create table test2 (a int, b int, c int, constraint uk_test2 unique (b, c));
create table test3 (a int, b int, c int, constraint uk_test3b unique (b), co...
Removing duplicate rows from table in Oracle
I'm testing something in Oracle and populated a table with some sample data, but in the process I accidentally loaded duplicate records, so now I can't create a primary key using some of the columns.
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