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Why does PostgreSQL perform sequential scan on indexed column?
Very simple example - one table, one index, one query:
4 Answers
4
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Django migration strategy for renaming a model and relationship fields
...different name, and the migration it creates will lose any data in the old table." Django 2.1 Docs For me, it was sufficient to create an empty migration, add the model renames to it, then run makemigrations as usual.
– hlongmore
Jan 15 '19 at 9:05
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How to Implement Custom Table View Section Headers and Footers with Storyboard
...simply drag a UIView onto the canvas, lay it out and then set it in the tableView:viewForHeaderInSection or tableView:viewForFooterInSection delegate methods.
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MySQL error 1449: The user specified as a definer does not exist
... ALTER statements
SELECT CONCAT("ALTER DEFINER=`youruser`@`host` VIEW ",
table_name, " AS ", view_definition, ";")
FROM information_schema.views
WHERE table_schema='your-database-name';
Copy and run the ALTER statements
How to change the definer for stored procedures
Example:
UPDATE `mysql`...
List of ANSI color escape sequences
... underlined (4) and the last part clears all this (0).
As described in the table below, there are a large number of text properties you can set, such as boldness, font, underlining, &c. (Isn't it silly that StackOverflow doesn't allow you to put proper tables in answers?)
Font Effects
╔══...
How do you use variables in a simple PostgreSQL script?
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Here's an example of using a variable in plpgsql:
create table test (id int);
insert into test values (1);
insert into test values (2);
insert into test values (3);
create function test_fn() returns int as $$
declare val int := 2;
begin
return (SELECT id FROM test ...
UITableView row animation duration and completion callback
Is there a way to either specify the duration for UITableView row animations, or to get a callback when the animation completes?
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How to alter a column's data type in a PostgreSQL table?
...entation here: http://www.postgresql.org/docs/current/interactive/sql-altertable.html
ALTER TABLE tbl_name ALTER COLUMN col_name TYPE varchar (11);
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Oracle的列操作(增加列,修改列,删除列)，包括操作多列 - 数据库(内核) - 清...
...(增加列,修改列,删除列)，包括操作多列增加一列： alter table emp4 add test varchar2(10);修改一列： alter table emp4 modify test varchar2(20);删除一列：alter 增加一列：
alter table emp4 add test varchar2(10);
修改一列：
alter table emp4 modify test va...
ActiveRecord OR query
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Use ARel
t = Post.arel_table
results = Post.where(
t[:author].eq("Someone").
or(t[:title].matches("%something%"))
)
The resulting SQL:
ree-1.8.7-2010.02 > puts Post.where(t[:author].eq("Someone").or(t[:title].matches("%something%"))).to_...