SQL Cheat Sheet

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','Waldibrücke')

Update

Update by condition

update tbl_kunde set name = 'Menzer' where name = 'Waltenspühl-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 = 'Müller'

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)

Login

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

Like

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 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, 'stück' 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 'Löschung 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('Löschung verwert; es bestehen noch Bestelungen für 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;

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