Cheat-Sheet on Janik von Rotz

Tmux Cheat Sheet

Wed, 11 Nov 2020 11:01:47 +0100

Tmux is a terminal multiplexer for Unix-like operating systems. It allows multiple terminal sessions to be accessed simultaneously in a single window. It is useful for running more than one command-line program at the same time. It can also be used to detach processes from their controlling terminals, allowing SSH sessions to remain active without being visible.

Install

See https://github.com/tmux/tmux/wiki/Installing for details.

Basics

Start new session.
tmux

Attach to last session.
tmux a

Show time.
ctrl + b t

Kill session.
tmux kill-session

Window

Create new window.
ctrl + b c

Rename new window.
ctrl + b ,

Close window.
ctrl + b &

Select window.
ctrl + b [0-9]

List windows.
ctrl + b w

Enter window index.
ctrl + b '

Swap windows.

ctrl + b :
swap-window -s 3 -t 1

Renumber windows. ctrl + b move-window -r

Pane

Split vertically.
ctrl + b %

Toggle last active pane.
ctrl + b ;

Split horizontally.
ctrl + b "

Switch to pane to the direction.
ctrl + b [h,j,k,l]

Close current pane.
ctrl + b x

Move pane right.
ctrl + b }

Move pane left.
ctrl + b {

Convert pane into a window.
ctrl + b !

Resize pane vertically. ctrl + b + ↑ ctrl + b + ↓

Resize pane horizontally. ctrl + b + ← ctrl + b + →

Session

Detach from session.
ctrl + b d

Attach to last session.
tmux a

Rename session.
ctrl + b $

List sessions.
ctrl + b s

Attach to named session.
tmux a -t name

Start new session.
ctrl + b :new

Copy Mode

Enter copy mode.
ctrl + b [ or v

Search down.
/

Search up.
?

Next keyword occurance.
n

Navigate up and down.
ctrl + u ctrl + d

Start selection.
space

Copy selection.
enter

Paste selection.
ctrl + b ]

List buffers.
ctrl + b :list-buffer

Paste buffer selection.
choose-buffer

Save buffer.
save-buffer buf.txt

Return to normal mode.
ctrl + c

Plugins

tmux-resurrect

Save session.
ctrl + b ctrl + s

Restore session.
ctrl + b ctrl + r

Another Vim Cheat Sheet

Thu, 06 Jun 2019 11:31:39 +0200

Getting started with Vim is not easy. Fueled by an entirely different ecosystem of plugins, scripts and obscure workflows it is difficult to see the advantage of using Vim. But, to watch experienced people using Vim is always impressive and makes one eager to learn it.

This cheat sheet does not intend to provide you with a list of plugins and dotfiles, but aims at giving an overview of the most common commands. I assmelbed this document while learning to vim.

In order to unsertand these command I recommend to read about the following Vim topics first:

leader key
plugins with plug
modes and buffers

Sections

Plugins

Plugins are managed by vim plug. My vim config including the list of plugins is available at GitHub - janikvonrotz/dotfiles.

fzf vim

Open file with fzf in new split or tab.

ctrl + t # tab split
ctrl + x # split
ctrl + v # vsplit

Search git files with key bindings.
leader + f

fugitive

Resolve merge conflicts.

# open conflicted file

# run diff command
:Gdiff

# navigate between remote and local version

# use diff put to select changes
dp

# write changes
:Gwrite

Checkout file from index.
:Gread

Show file history.
:Gblame

Rebase interactive.

# Rebase last 10 commits
git rebase -i HEAD~10

# Navigate and replace word
cw

# Enter letter for commands
d

vim indent guides

Show indents.
leader + ig

Basics

Save current file.
:w

Override current file.
:w!

Save and quit.
:wq or ZZ

Reload current file.
:e

Quit vim.
:q

Quite all splits and tabs.
:qa

Profile

Reload vim profile.
:so $MYVIMRC or :source %

Modes

Enter visual character selection mode.
v

Enter visual line selection mode.
V

Enter insert mode. i

Enter insert mode after current character.
a

Exit mode.
ctrl + c or ESC

Open new or existing file inside vim.
:e /path/to/file

Open file browser inside vim.
:e /path/to/direcotry

Navigate with keys.

h # left
j # down
k # up
ö # right
w # word
e # end
b # back
$ # end of line
0 # beginning of line

Navigate pages.

ctrl + u # page up
ctrl + d # page down
G # go to bottom
gg # go to top

List previous opened files.
:jumps

Open the last file.
:e#

Navigate search results.

n # next
shift + n # previous

Session

Save the current session.
:mksession

Open vim with session file.
vim -S Session.vim

Edit

Undo changes.
u

Redo changes.
ctrl + r

Copy and paste.

# cut current selection
d
# delete word
dw
# copy current selection
y
# cut the current line
dd
# copy current line
yy
# paste
p

Search and replace in file.
:%s/old/new/g

Add line below current line.
o

Tell vim to not autoindent or otherwise alter the format of your pasted text.
:set paste or :set nopaste

Move line up or down.
ddp and dd{j,k}p or :m{+,-}{i} and :m{i}

Select

Select text between character.
vi{c}

Select current word.
vw

Window

Split window vertically.
:vs

Split window horizontally.
:sp

Switch between splits.
ctrl + w & {h,j,k,l}

Leader

Set leader key.
:let mapleader = "-"

Tabs

Open file in new tab.
:tabnew /path/to/file

Open multiple files in tabs.

:args path/to/files/*
:tab all

Navigate tabs.

gt # go to next tab
gT # go to previous tab
{i}gt # go to tab in position i

Shell

Run shell command in split pane.
:new | 0read ! command

Buffer

Reload all buffers.
:bufdo e

Sources

Learn Vimscript the Hard Way

Jesse Leite - It’s dangerous to Vim alone! Take Fzf

Thoughtbot - Vim Splits - Move Faster and More Naturally

Photography Filter Cheat Sheet

Sun, 12 Jul 2015 21:58:09 +0000

Ever wondered what effect photography filters have on the resulting image? Well here’s a handy guide:

Source: Zippi.co.uk - The Photography Filters Cheat Sheet

SQL Cheat Sheet

Thu, 02 Jul 2015 18:16:54 +0000

You can get the latest version of this SQL cheat sheet here: https://gist.github.com/janikvonrotz/6e27788f662fcdbba3fb

SQL languages

DDL is short name of Data Definition Language, which deals with database schemas and descriptions, of how the data should reside in the database.

DML is short name of Data Manipulation Language which deals with data manipulation, and includes most common SQL statements such SELECT, INSERT, UPDATE, DELETE etc, and it is used to store, modify, retrieve, delete and update data in database.

DCL is short name of Data Control Language which includes commands such as GRANT, and mostly concerned with rights, permissions and other controls of the database system.

Datatypes

Text types

Data type	Description
CHAR(size)	Holds a fixed length string (can contain letters, numbers, and special characters). The fixed size is specified in parenthesis. Can store up to 255 characters
VARCHAR(size)	Holds a variable length string (can contain letters, numbers, and special characters). The maximum size is specified in parenthesis. Can store up to 255 characters. Note: If you put a greater value than 255 it will be converted to a TEXT type
TINYTEXT	Holds a string with a maximum length of 255 characters
TEXT	Holds a string with a maximum length of 65,535 characters
BLOB	For BLOBs (Binary Large OBjects). Holds up to 65,535 bytes of data
MEDIUMTEXT	Holds a string with a maximum length of 16,777,215 characters
MEDIUMBLOB	For BLOBs (Binary Large OBjects). Holds up to 16,777,215 bytes of data
LONGTEXT	Holds a string with a maximum length of 4,294,967,295 characters
LONGBLOB	For BLOBs (Binary Large OBjects). Holds up to 4,294,967,295 bytes of data
ENUM(x,y,z,etc.)	Let you enter a list of possible values. You can list up to 65535 values in an ENUM list. If a value is inserted that is not in the list, a blank value will be inserted.Note: The values are sorted in the order you enter them.You enter the possible values in this format: ENUM(‘X’,‘Y’,‘Z’)
SET	Similar to ENUM except that SET may contain up to 64 list items and can store more than one choice

Number types

Data type	Description
TINYINT(size)	-128 to 127 normal. 0 to 255 UNSIGNED*. The maximum number of digits may be specified in parenthesis
SMALLINT(size)	-32768 to 32767 normal. 0 to 65535 UNSIGNED*. The maximum number of digits may be specified in parenthesis
MEDIUMINT(size)	-8388608 to 8388607 normal. 0 to 16777215 UNSIGNED*. The maximum number of digits may be specified in parenthesis
INT(size)	-2147483648 to 2147483647 normal. 0 to 4294967295 UNSIGNED*. The maximum number of digits may be specified in parenthesis
BIGINT(size)	-9223372036854775808 to 9223372036854775807 normal. 0 to 18446744073709551615 UNSIGNED*. The maximum number of digits may be specified in parenthesis
FLOAT(size,d)	A small number with a floating decimal point. The maximum number of digits may be specified in the size parameter. The maximum number of digits to the right of the decimal point is specified in the d parameter
DOUBLE(size,d)	A large number with a floating decimal point. The maximum number of digits may be specified in the size parameter. The maximum number of digits to the right of the decimal point is specified in the d parameter
DECIMAL(size,d)	A DOUBLE stored as a string , allowing for a fixed decimal point. The maximum number of digits may be specified in the size parameter. The maximum number of digits to the right of the decimal point is specified in the d parameter

Date types

Data type	Description
DATE()	A date. Format: YYYY-MM-DDNote: The supported range is from ‘1000-01-01’ to ‘9999-12-31’
DATETIME()	*A date and time combination. Format: YYYY-MM-DD HH:MI:SSNote: The supported range is from ‘1000-01-01 00:00:00’ to ‘9999-12-31 23:59:59’
TIMESTAMP()	*A timestamp. TIMESTAMP values are stored as the number of seconds since the Unix epoch (‘1970-01-01 00:00:00’ UTC). Format: YYYY-MM-DD HH:MI:SSNote: The supported range is from ‘1970-01-01 00:00:01’ UTC to ‘2038-01-09 03:14:07’ UTC
TIME()	A time. Format: HH:MI:SSNote: The supported range is from ‘-838:59:59’ to ‘838:59:59’
YEAR()	A year in two-digit or four-digit format.Note: Values allowed in four-digit format: 1901 to 2155. Values allowed in two-digit format: 70 to 69, representing years from 1970 to 2069

Database

Create

create database dbname;

Drop

drop database dbname;

Table

Check if not exit and create

IF OBJECT_ID('tbl_kunde', N'U') is not null
	drop table tbl_kunde;
GO
create table tbl_kunde (
  id_kunde int not null primary key,
  fi_moral_nr int,
  name varchar(25) not null,
  vorname varchar not null,
  wohnort varchar
);
GO

Alter Table

Primary Key

ALTER TABLE tbl_kunde ADD PRIMARY KEY (id_kunde);

Foreign Key

ALTER TABLE tbl_kunde ADD CONSTRAINT FK_fi_moral_nr FOREIGN KEY (fi_moral_nr)
  REFERENCES tkey_moral
  ON UPDATE CASCADE
  ON DELETE SET NULL;

Constraint

ALTER TABLE tkey_moral ADD CONSTRAINT PK_id_moral_nr PRIMARY KEY (id_moral_nr);
ALTER TABLE tbl_kunde ADD CONSTRAINT FK_fi_moral_nr FOREIGN KEY (fi_moral_nr)
  REFERENCES tkey_moral
  ON UPDATE CASCADE
  ON DELETE SET NULL;

Insert

Selected fields

insert into tkey_moral (id_moral_nr, moral_bez) values (1, 'gut'), (2, 'schlecht'), (3, 'schlecht');

All fields

INSERT INTO tbl_kunde VALUES (3838,1,'Meier','Laura','WaldibrÃ¼cke')

Update

Update by condition

update tbl_kunde set name = 'Menzer' where name = 'WaltenspÃ¼hl-Menzer'
update tass_police set praem_stufe = 101 where praem_stufe = 108

Delete

All

delete from tbl_kunde

Condition

delete from tkey_moral where id_moral_nr = 4
delete from tbl_kunde where vorname = 'Peter' and name = 'Fischer' or vorname = 'Martin' and name = 'MÃ¼ller'

Index

Create

create unique index ix_kund_name on tbl_kunde (name)

Disable

alter index ix_kund_name on tbl_kunde disable

Rebuild

alter index ix_kund_name on tbl_kunde rebuild

Reorganize

alter index ix_kund_name on tbl_kunde reorganize

Drop

drop index ix_kund_name on tbl_kunde

Alter

drop index ix_kund_name on tbl_kunde

Type

create

create type tp_moralisches from numeric(9,0)

change password

alter login stud23 with password = 'hello' old_password = 'pass_wd23'

User

create

create user romulus from login romulus

drop

drop user romulus

Grant/ Revoke

Available permissions: CREATE DEFAULT, CREATE FUNCTION, CREATE PROCEDURE, CREATE ROLE, CREATE TABLE, CREATE TYPE, CREATE VIEW, DELETE, EXECUTE, INSERT, SELECT, UPDATE

Grant rights

grant select, insert, delete, references, update to romulus

Grant refrences

grant references (id_moral_nr) on tkey_moral to romulus

Revoke

revoke insert, delete, references, update to romulus

Role

Create

create role verkauf

Add member

exec sp_addrolemember 'verkauf', 'anna'

Grant Role

Grant rights

grant select, update, insert, delete on tbl_kunde to verkauf

View

Create detailed

CREATE VIEW v_kunden (id, name, vorname, ort, police, gebiet) AS
  SELECT k.id_kunde, k.name, k.vorname, k.wohnort, v.vers_bez,
         v.vers_gebiet
    FROM tbl_kunde AS k, tkey_versicherung AS v, tass_police AS p
      WHERE k.id_kunde = p.id_fi_kunde
        AND p.id_fi_vers_art = v.id_vers_art;

Create simple

create view plain as select id_kunde, name, vorname from tbl_kunde

Create advanced

create view v_umsatz as select sum(cast(bezahlt as float)) as 'Umsatz aus Policen' from tass_police

Select

Basic

select dt_jahr from dbo.tbl_stueck

Condition

select dt_jahr from dbo.tbl_stueck where dt_jahr is not null

Order

select dt_jahr from dbo.tbl_stueck
where dt_jahr is not null
order by dt_jahr desc

Distinct

select distinct dt_jahr from dbo.tbl_stueck
where dt_jahr is not null
order by dt_jahr asc

And Condition

select * from tbl_stueck where dt_jahr = 1970 and dt_zeit > 3

Between

select * from tbl_stueck where dt_jahr = 1970 and dt_zeit between 3 and 10

select * from tbl_stueck where dt_stueck_titel like 'Let%'

Count

select count(dt_stueck_titel) from tbl_stueck where dt_stueck_titel like 'Let%'

Having and without join

select i.dt_name, count(s.dt_stueck_titel) from tbl_stueck as s, tkey_interpret as i
where  s.fi_interpret = i.id_interpret
group by i.dt_name
having count(s.dt_stueck_titel) >10
order by count(s.dt_stueck_titel) de

Join the hard way

Inner Join

select s.dt_stueck_titel, i.dt_name
from tbl_stueck as s, tkey_interpret as i
where  s.fi_interpret = i.id_interpret
order by s.dt_stueck_titel

Multi Join

select sa.id_jahr, st.dt_stueck_titel, ip.dt_name
from tbl_stueck as st, tass_stueck_sampler as ss, tkey_sampler as sa, tkey_interpret as ip
where ss.id_fi_stueck_nr = st.id_stueck_nr 
and ss.id_fi_jahr = sa.id_jahr
and  st.fi_interpret = ip.id_interpret
order by  st.dt_stueck_titel

Join the right way

Inner Equi Key Joining

select dt_stueck_titel, dt_name
from tbl_stueck join tkey_interpret 
on fi_interpret = id_interpret
order by dt_stueck_titel

Multi Inner Equi Key Joining

select id_fi_jahr, dt_stueck_titel, dt_name
from tbl_stueck
join tass_stueck_sampler on id_fi_stueck_nr = id_stueck_nr
join tkey_interpret on fi_interpret = id_interpret
order by  dt_stueck_titel

About Joins

![sql 1=“summary” language=“join”]/sql

SELECT customers.id, customers.name, items.name, customers.state 
FROM customers, items
WHERE customers.id=seller_id
ORDER BY customers.id

Join tables -> Joining two tables together in a query output. The third line is important because it shows how the two tables are related (in this case it is their key values).

SELECT customers.name, items.name FROM customers
LEFT OUTER JOIN items ON customers.id=seller_id

LEFT/RIGHT OUTER JOIN -> Takes the table left of the word ‘LEFT’ or ‘RIGHT’ (in this case customers) and joins it regardless of whether it has any values or not. So the above statement shows all users/customers, even if they aren’t selling anything.

Select with Subqueries

Select max and min values

select dt_stueck_titel as Titel, dt_zeit as Zeit
from tbl_stueck
where dt_zeit = (select max(dt_zeit) from tbl_stueck)
or dt_zeit = (select min(dt_zeit) from tbl_stueck)
order by dt_zeit;

Select with query in condition

select dt_stueck_titel as Titel, dt_zeit as Zeit
from tbl_stueck
where dt_zeit between (select avg(dt_zeit) from tbl_stueck)*0.9
and (select avg(dt_zeit) from tbl_stueck)*1.1
order by dt_zeit;

Select query as value

select dt_stueck_titel as Titel,
dt_zeit/(select avg(dt_zeit) from tbl_stueck)*100 as Zeit
from tbl_stueck
where dt_stueck_titel = 'You Shook Me'

Union

Unify two result sets with a condition

select *  from
(select dt_stueck_titel as titel, 'stÃ¼ck' as 'type' from tbl_stueck
union
select dt_name as titel,  'inter' as 'type' from tkey_interpret
union
select dt_stao as titel,  'stao' as 'type' from tkey_standort) as t
where t.titel like '%boy%'

Transactions

Run a transaction

begin transaction
update tass_police set bezahlt = 0 where id_fi_kunde = 3533 and id_fi_vers_art = 1700
commit
-- or rollback

Function

A function can be called from inside a statement just like any other function and can return a scalar value.

Create - Get value from table

create function f_plic_bez()
  returns decimal(10,2)
  as begin
  return (select sum(bezahlt) from tass_police)
  end;
go
select  dbo.f_plic_bez() AS 'Summe aller bezahlten Leistungen'
go

Drop

drop function f_bezahlt_versich

Create - With parameters

create function f_rabatt(@name varchar(40), @vers varchar(30))
  returns int
  as begin
  return (select (praem_stufe-100)*10 from  tass_police
  join tbl_kunde on id_fi_kunde = id_kunde
  join tkey_versicherung on id_fi_vers_art = id_vers_art
  where name = @name and vers_bez = @vers)
  end

Procedure

Stored procedures are stored as precompilated code (stored routine) and called by the programmer wherever it wants to fire. Stored procedure can return value(s).

Create and execute

CREATE PROCEDURE p_polic_del @fname VARCHAR(30), @versich VARCHAR(30)
  AS
  BEGIN
    DELETE FROM tass_police
      FROM tbl_kunde, tkey_versicherung
        WHERE name = @fname
          AND id_kunde = id_fi_kunde
          AND id_fi_vers_art = id_vers_art
          AND vers_bez = @versich
    IF @@ROWCOUNT = 0
      PRINT 'Police existiert nicht.'
      ELSE PRINT 'LÃ¶schung vollzogen.'
  END
GO

EXECUTE p_polic_del 'Meier', 'Taggeld';

Variables

Declare

DECLARE @veraenderung SMALLINT = 180;
DECLARE @neue_summe INT;

Trigger

Triggers are named database objects fired automatically when insert, delete, update (or other event) occurred, there can be no explicit invocation. Trigger can not return any data.

Create simple

create trigger t_ort on tbl_kunde
  after insert, update
  as beginn
    set @ort = select wohnort from inserted)
    if((@ort like '/^[A-Z]') && len(@ort) < 2)
      rollback transaction
  end
end

Drop

drop trigger t_ort

Checks the referential integrity

create trigger t_bst_mut on bst
	for insert, update
	as
	begin
		set nocount on;
		if(select id_fi_k from inserted) NOT IN (select id_kund from knd)
			begin
				raiserror('Es besteht kein entsprechender Kunde.', 15, 1);
				rollback transaction;
			end
	end;

Replaces on delete no action

create trigger t_ku_del on knd
	for delete
	as
	begin
		set nocount on;
		if((select id_kunde from deleted) IN (select id_fi_k from bst))
			begin
				raiserror('LÃ¶schung verwert; es bestehen noch Bestelungen fÃ¼r diesen Kunden.', 15, 1)
				rollback transaction
			end
	end;

Replaces on update cascade

create trigger t_update_knd on knd
	after update
	as
	begin
		set nocount on;
		update bst set id_fi_k = (select id_kund from inserted)
	end;

Replaces on delete cascade

create trigger t_delete_knd on knd
	after delete
	as
	begin
		delete from bst where id_fi_k = (select id_kund from deleted)
	end;

Cheat-Sheet on Janik von Rotz

Tmux Cheat Sheet

Install

Basics

Window

Pane

Session

Copy Mode

Plugins

tmux-resurrect

Another Vim Cheat Sheet

Sections

Plugins

fzf vim

fugitive

vim indent guides

Basics

Profile

Modes

Navigation

Session

Edit

Select

Window

Leader

Tabs

Shell

Buffer

Sources

Photography Filter Cheat Sheet

SQL Cheat Sheet

SQL languages

Datatypes

Database

Table

Alter Table

Insert

Update

Delete

Index

Type

Login

User

Grant/ Revoke

Role

Grant Role

View

Select

Join the hard way

Join the right way

About Joins

Select with Subqueries

Union

Transactions

Function

Procedure

Variables

Trigger