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SQL- Study note

By Maggie Zhou

Sep, 2008

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Preface

This is one of my study note for SQL Main part of this note is from

Head First SQL: Your Brain on SQL -- A Learner's Guide

By Lynn Beighley

August 2007

Pages: 607

Series: Head First

ISBN 10: 0-596-52684-9 | ISBN 13: 9780596526849

This is a great book for beginner, and you will have a lot

of fun when you go through this book (trust me, this is

not a commercial)

But it isnt only from this book:

I organized this note in my understanding way.

I added several concepts which I think are important

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Basic concepts

SQL: /sikwl/, Structured QueryLanguage,

RDBMS: Relational DataBase

Management Systems SQL Appeared in 1974

MySQL: SQL/PSM

SQL/Persistent Stored Module (as in ISO

SQL:2003)

Oracle: PL/SQL

Procedural Language/SQL (based on Ada)

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MySQL installation

MySQL community ServerOfficial free version of the MySQL RDBMS

Steps to install MySQL on windowsDownload

http://dev.mysql.com/downloads/ Choose windows from list

Choose Windows ZIP/Setup.exe option

Pick a mirror

Run Setup Wizard

Choose typical Install to default location: c:\program files\mysql\mysql

server 5.0

Finally install it

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Create (1)

Case insensitive DatabaseCREATE DATABASE name

Table

CREATE TABLE name(

data_name1 CHAR/CHARACTER(x~256),

data_name2 DEC/DECIMAL(x,x),

data_name3 INT/INTEGER,

data_name4 BLOB,data_name5 DATE,

data_name6 DATETIME/TIMESTAMP,

data_name7 VARCHAR(x~256)

);

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Create (2)

Columns / AttributesMandatory value

(

data_name CHAR(10) NOT NULL,

)

set default value

(

data_name DEC(3.2) NOT NULL DEFAULT 1.00,

)

Use keyword as columns name

BAD, but can do INT is ok

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Data type (1)

BOOLEANRDBMS store a 1 for true, 0 for false

You can insert: 1/true, 0/false, null

INTUnsigned integer: values in the range 0 to

4294967295

Signed integer: INT(SIGNED)

SMALLINT

BIGINT

MySQL also has: TINYINT, MEDIUMINT

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Data type (2)

DATE and TIMEDATE: yyyy-mm-dd

DATATIME: yyyy-mm-dd hh:mm:ss

TIMESTAMP: yyyymmddhhmmss

TIME: hh:mm:ss

DATE_FORMAT tells function the date_formatyou wantSELECT

DATE_FORMAT (date, %M %Y)

FROM table_name;

Result will be: Auguest 2007

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CAST

CAST (column, TYPE); Types

CHAR()

DATE, DATETIME, TIME

DECIMALSIGNED [INTEGER]

UNSIGNED [INTEGER]

CAN

Be included inside the INSERT, SELECT CANT

DEC to INT

TIME, DATE, DATETIEM, CHAR to DEC, or INT

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Maintain

Change databaseUSE database_name;

Check structure of table

DESC table_name;

Check table content

SELECT * FROM table_name

Change

Please see from Slides 23

Delete

DROP TABLE table_name;

Only can use on empty table

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Add data

Insert dataINSERT INTO table_name

(column_name1, column_name2,)

VALUES (value1, value2,); For the AUTO_INCREMENT column, can use , instead input

value Synax for column

Using column name can control the insert order, the valueorder should match

Not using column name, value need including all the value,

in exact order in table Synax for value:

CHAR, VARCHAR, DATE, BLOB need single quote

INT, DEC do not use quote

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Select (1)

Show all data & all columnSELECT * FROM table_name;

Show chosen data & all columnSELECT *

FROM table_name

WHERE column_name = value; Can use =, >, =,

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Select (2)

Show multiple choose conditionsSELECT *

FROM table_name

WHERE condition1

AND, OR

AND: match all the conditions

OR: match only one condition is enough

Condition2;

Comparison operators=, >, =,

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Select (3)

Wide cardSELECT *FROM table_name

WHERE column_name LIKE %XX; % any number of unknown characters

_ just only one unknown character

Given RangeSELECT *

FROM table_name

WHERE column_name BETWEEN xx AND xx;

Given Group

SELECT *FROM table_name

WHERE column_name IN (value, value,); IN the data match conditions

NOT IN the data do not match conditions

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Select (4)

NOT conditionsCombine AND, OR, IS with NOT

Right after AND, OR AND NOT

IS NOT NULL means WHERE NOT name IS NULL

Could do, but you shouldnt do double

negative

Bad: WHERE NOTcolumn value;

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Database design

Steps to designPick one thing your table want to describe

Make a list of information using the table

Break down information into pieces and organizing table

Atomic dataColumn with atomic data cant have several value of the

same type of data

Table with atomic data cant have multiple columns with

same type of data

Normal tableNormal table wont have duplicate data

With less data to search through

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1NF FIRST NORMAL FORM

Each row of data must only contain atomicvalues

Each row of data must have a unique

identifier

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Primary key Create

CREATE TABLE table_name

(key_name data_type NOT NULL,PRIMARY KEY (key_name)

);

OR

CREATE TABLE table_name

(key_name data_type NOT NULL PRIMARY KEY,

);

Key:Can not be NULL

Must be compact

Can not be changed

Auto incrementally(key_name INT NOT NULL AUTO_INCREMENT PRIMARY KEY,

);

Data has same key value wont be accepted

The key can be overwritten you still can make own value

AUTO-INCREMENT

Only one per table, must be INT, cannot beNOT NULL

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Delete row

Delete row/rows base on conditionDELETE FROM table_name

WHERE condition;

Without condition, you will delete alldata

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ALTER Table (1)

All about the columns table structure Change

Change name, data type of existing column

ModifyData type or position of existing column

Add

Add new column Drop

Delete column from table

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ALTER Table (2) ADD COLUMN

Alter tableALTER TABLE table_name

Add column

ADD COLUMN column_name type NOT NULL

AUTO_INCREMENT FIRST, (dont forget , )ADD PRIMARY KEY (column_name);

OR

ADD COLUMN column_name type

AFTER another_column_name; Define the position;

Can use: FIRST, LAST, AFTER, BEFORE

Even can use: SECOND, FIFTH

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ALTER Table (3) CHANGE/RENAME

Rename tableALTER TABLE table_name

RENAME TO new_table_name

Change column name and typeALTER TABLE table_name

CHANGE COLUMN column_name

new_column_name new_type ,

;

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ALTER Table (3) MODIFY

Modify columnALTER TABLE table_name

MODIFY COLUMN column_name

new_type/size;

Cannot change order of columns

It wont matter, due to you can use SELECT

to control order

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ALTER Table (3) DROP

Delete columnALTER TABLE table_nameDROP COLUMN column_name;

Remove AUTO_INCREMENTALTER TABLE table_name

CHANGE column_name new_column_namenew_type; withoutAUTO_INCREMENT Just simply without AUTO_INCREMENT

After remove AUTO_INCREMENT, then you candrop the PRIMARY KEY, otherwise, will be error

Remove PRIMARY KEYALTER TABLE table_name

DROP PRIMARY KEY;

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String functions (1)

SELECT RIGH

T(column_name, number) FROM table_name;Can use RIGHT, LEFT start from right or left side of

column

Number: how many characters to select

SELECT SUBSTRING_INDEX (column_name,key, index)

FROM table_name;

SUBSTRING_INDEX

subestring, everything in frontof it

key the key character, key string is looking for

Index 1 means looking for the first key, 2 meanslooking for the second key

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String functions (2)

SUBSTRING(string, index, index); SUBSTR(string, index)Shortening the length of the string start right after the index

UPPER(string);

LOWER(string);

REVERSE(string);

LTRIM( string);

RTRIM(string );

LENGTH(string);

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Copy

Change all the data in a columnUPDATE table_name

SET column_name = new_value;

Copy columnUPDATE table_name

SET column_name = source_column_name;

Can use all the string function

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Group data (1) Category

UPDATE table_name

SET category = value WHERE conditions

Update statements help you classify data

Update statements order matters, due to they maychange same value

group data data have same value in the

column

SELECT * FROM table_nameGROUP BY column_name;

Only show the only one and the first one record

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Group data (2)

Choose valueUPDATE table_nameSET column_name =

CASE

WHEN condition1 THEN new_value1

WHEN condition2 AND condition3 THEN new_value2

ELSE new_value3 elseisoptional

END;

or

END WHERE condition4; usethisconditiontochoosespecificrows;

CASE expression can be used with SELECT,INSERT, DELETE and UPDATE

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Order data (1)

Show ordered dataSELECT column_names,

FROM table_name

WHERE conditions,

ORDER BY column_name;

Order rulesNon-alphabet

Number < text character

NULL < Number

NULL < alphabet character

Uppercase < Lowercase

Space < number

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Order data (2)

Ordered data by multiple columnsORDER BY column_name1,

column_name2, ;

First order by column_name1, then 2

Descending order

ORDER BY column_name DESC;

Can use DESCRIBE for DESC table_name

But can not use DESCENDING

Default order

ASC means default order

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Calculate data (1)

NULL is not used by all the calculationfunctions (absence)

SUM()SELECT columns, SUM (column_name1)

FROM table_name

GROUP BY column_name1;

Group all the date with same value in column_name1

Sum all value within the group

AVG()SELECT columns, AVG (column_name1)

FROM table_name


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Calculate data (2)

MIN()SELECT columns, MIN (column_name1)

FROM table_name


MAX()

SELECT columns, MAX (column_name1)

FROM table_name


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Calculate data (3)

COUNT(): Count number of the rows in the columnSELECT COUNT (column_name)

FROM table_name;

GROUP BY another_column;

DISTINCT: Remove all the duplicate records

SELECT DISTINCT column_nameFROM table_name

Be careful DISTINCT is a keyword

DISTINCT + COUNT() use to calculate the number ofabsolute different data

DISTINCT is used to remove duplicate record

COUNT is used the count the number of the rows

Thus this avoid count duplicate records

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Calculate data (4)

Limit the number of resultsSELECT columns, SUM (column_name1)

FROM table_name


ORDER BY SUM (column_name1);LIMIT number;

ORDER BY must after the GROUP BY

Limit number by rangeLIMIT index1, index2

index1 is start point Start from 0

Index2 is number of showing result

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SCHEMA

Schema is : Adescription of thedata (columns andtables) in yourdatabase, along with

any other relatedobjects and the waythey all connect

Diagram for tabledesign

Split the non-atomicfield into anothertable

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Connect tables (1)

FOREIGN KEYIs a column in a table that reference the

PRIMARY KEY of another table

Child_tables FOREIGN KEY is the PRIMARY KEY

of Parent_table FOREIGN KEY is parent key, is from parent table

FOREIGN KEY can be different name

FOREIGN KEY can be NULL

means there is no matching primary key in parenttable

FOREIGN KEY dont have to be unique

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Connect tables (2)

Foreign key + constraintReferential integrity

Only be able to insert values into your

foreign key that in parent table

Use a foreign key to reference a unique value

in the parent table

UNIQUE

Not available in MySQL

CHECK

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Create child table (1)

CREATE TABLE table_name (Columns ,

child_column_name INT NOT NULL, Define child table column name, type,

Dont forget ,CONSTRAINT parent_id_fk

name: parent_table_name +parent_column_name + fk(foreign key)

FOREIGN KEY (child_column_name)

REFERENCES parent_table_name(parent_column_name)

) ; book has mistake here

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Relationships

One-to-one: plain lineFaster queries

Isolate column to avoid NULL in main table

Make part of data less accessible

Put large piece data into a separate table

One-to-many: black arrow line, only onearrow at the end of many

Many-to-many: black arrow line, arrows atboth endsTwo one-to-many relationships with ajunction table in between

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Junction table

Avoid duplicate data in many-to-manyrelationship

A table step in between two many-to-

many tables and simplify therelationship to one-to-many.

Contain the two primary key columns of

the two related table.

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Composite primary key

Is a primary key Uses several columns together to form

a unique primary key in a table

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Dependent column

The A column functionally depend B column, A must change when Bs data is modified

Notations

T.x ; T.y

Relational table T, column y is functionally dependenton column x

Partial functional dependency

Non-key column is dependent on some but not all, of

the columns in a composite primary key Transitive functional dependency

Non-key column is related to any of the other non-

key columns

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2NF- Second Normal Form

2NF focuses on how the primary keyrelates to the data

2NF rules:

Be in 1NF

Have no partial functional dependencies

1NF is also 2NF

If all the columns in the table are part of the

primary key

OR

It has a signal column primary key

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3NF- Third Normal Form

3NF rules:Be in 2NF

Have not transitive dependencies

Table is in 2NFIf it has an artificial primary key and no

composite primary key

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Pre-populate table (1)

Create table, then insert with selectCREATE TABLE table_name normalway

(

Create Primary_key column,

Column_name

);

INSERT INTO table_name (column_name)

SELECT column_name

FROM parent_table_nameGROUP BY column_name


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Create table with select, then alter to addprimary keyCREATE TABLE table_name

AS

SELECT column_name

FROM parent_table_nameGROUP BY column_name


ALTER TABLE table_name

ADD COLUMN primary_key column; AS funneling all the output of the SELECT

into the new table

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Create, select and insert at the same timeCREATE TABLE table_name

(

Create Primary_key column,

Column_name) AS

SELECT column_name

FROM parent_table_name

GROUP BY column_name ORDER BY column_name

;

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alias

SQL allow to temporarily give the columnsand tables new names

Column aliasesSELECT column_name AS column_alias

temporary

FROM table_nameGROUP BY column_alias

ORDER BY column_alias;

Table aliases: called correlation nameSELECT column_name AS column_alias

FROM table_name AS table_alias

OR

FROM table_name table_alias without AS

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Cartesian Join (1)

Different names: Cartesian product, crossproduct, cross join, no join

SELECT TableA.column1, TableB.column2

FROM TableA CROSS JOIN TableB

OR FROM TableA , TableB

COMMA JOIN use , instead of CROSS JOIN

Return every row from table_A cross withevery row from table_B

The column which has more values, thecolumn show up in groups.

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Cartesian Join (2)

UsageCan help with fix the joins

Used to test the speed of the RDBMS and its

configuration

Cartesian join is a type of inner join

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InnerJoin

InnerJoin combine records from two tablesusing comparison operator in a condition

Columns only return the matched join rows

InnerJoin is a Cross Join with some result rows

removed by a condition in the query Create InnerJoin

SELECT A.columns, ... , B.columns, , columns

From table_A AS A INNER JOIN Table_B AS B

ON A.column = B.column; relationship Also can use WHERE

Matches the two columns in different tables

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InnerJoin in actions

Equijoin INNER JOIN

ON A.id = B.id;

Inner join test for equality

Non-euqijoin

INNER JOIN ON A.id B.id;

Inner join test for inequality

Natural join

SELECT columns, FROM table_A NATURAL JOIN table_B;

Inner join identify matching column names

Do not need ON conditions

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Subquery (1)

A query is wrapped within anotherquery

OUTER query

INNER query Subquery

Take the result of one query and use it

as the input to another query

Can be used to

Avoid duplicate data

Make queries more dynamic

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Subquery (2)

Subquery is always a single SELECT statement

Subqueries are always inside () parentheses

Subqueries do not get their own ; semicolonOne ; semicolon goes at the end of entire query

Subqueries can be show up in four places

SELECT clauseSELECT column List

FROM clause

HAVING clause

Subqueries can be used withINSERT

DELETE

UPDATE

SELECT

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Subquery (3)

SELECT columns FROM table_A

NATURAL JOIN

table_B WHERE column_name

IN (SELECT column FROM table_C);

SubqueryAll others are OUTER query

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Subquery (4)

SELECT columns

FROM table_name

WHERE condition (subquery)

Usually, Subquery return single value, one rowfrom one column

where column = (subquery)Subquery return more than one value when using

IN

where column IN (subquery)

Subquery also can use WHERE condition Can use subquery instead the INNER JOIN

Join combine all columns from two tables

Subquery can only use the columns from one table

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Subquery as SELECT column

Used as a column expression inSELECT statement

Can only return one value from one

columnSELECT columns

(SELECT column

FROM table

WHERE conditions)

FROM table

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Noncorrelated subquery

Correlated subquery is slow Noncorrelated subquery

Subquery stands alone

Doesnt reference anything from the outer query

Inner query in no way depends on valuesfrom the outer query

It can run as a standalone query

Noncorrelated subquery with IN, NOT INUse IN, NOT IN to test if the values returned in

subquery are members of a set(or not)

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Correlated subquery

Correlated subqueryInner query relies on the outer query before it

can be resolved

Use the same alias or correlated name from

the outer query

Common use

Find all the rows in the outer query for which

no rows exist in a related tableEXISTS

NOT EXISTS

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EXISTS and NOT EXISTS EXISTS: Find the results in table_A which at least shows

in table_B onceSELECT columns

FROM table_A

WHERE EXISTS

(SELECT * FROM table_B

WHERE condition usuallyconditioninvolveouterquery);

NOT EXISTS: Find the results in table_A which is not intable_BSELECT columns

FROM table_AWHERE NOT EXISTS

(SELECT * FROM table_B

WHERE condition usuallyconditioninvolveouterquery

);

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OuterJoin (1)

Deal with two tables which dont have anymatching counterpart

Relationship between two tables

One-to-many relationship

LEFT OUTER JOIN:SELECT columns

FROM Left_table

LEFT OUTER JOIN Right_table

ON relationship;

Takes all the rows in the Left_table and

matches them to rows in the Right_table.

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OuterJoin (2) RIGHT OUTER JOIN:

SELECT columns

FROM Left_table

RIGHT OUTER JOIN Right_table

ON relationship;

Takes all the rows in the Right_table and matches them to

rows in the Left_table.Reverse the LEFT OUTER JOIN Reason to use these two: change the key word is easier than

change the order of the tables

Similar with INNER JOIN but not OUTER JOIN givesall the rows whetherthere is a match with the other

table or notUse NULL value to show no match exists

In LEFT OUTER JOIN, NULL means the Right_table has no valuethat correspond to the Left_table

Some RDBMS use FULL OUTER JOIN, but not inMySQL, SQL Server or Access

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Self-join (1)

Self-referencing foreign keymeans that it is a key is referencing another field inthe same table

The primary key of a table used in that sametable for another purposeThe primary key use to describe other attribute of the

elements

Join a single table to itself

Used to simulate having two tables with

exactly same informationIn a normalized database, would never have two

copies of the same table

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Self-join (2)

Use different alias to separate the sametable act as two tables

SELECT alias1.column, , alias.column, ,

FROM table_name AS alias1

INNER JOIN

Table_name AS alias2

ON alias1.primary_key =

alias2.self_referencing_key;

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Union Combine the results of queries

Combine the results from multiple tablesSELECT column FROM table_A

UNION

OR

UNION ALL Return every match, including the duplicate values

By default, results removed duplicate values

SELECT column FROM table_B

ORDER BY column; Only can add ORDER BY at the end of the statement

Rules:

Number of columns in each SELECT statement must matchMust have same expression and aggregate function in each

SELECT statement

Order of SELECT statement doesnt matter

The data types in the columns need to either same orconvertible to each other

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INTERSECT & EXCEPT

UNION, INTERSECT, EXCEPT are usedto find parts of queries that overlap

INTERSECT:

Returns only those values that are in the first

query and also in the second query

EXCEPT:

Returns only those values that are in the first

query but not in the second query

MySQL do not have INTERSECT and

EXCEPT

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Subqueries vs. Joins (1) Subquery ORDER BY + LIMIT

SELECT title FROM job_listingsWHERE salary =

(SELECT MAX(salary) from job_listings);

Howabout:SELECT title FROM job_listings

ORDER BY salary DESC

LIMIT 1; Self-join subquery

SELECT f1.name, f2.name AS boss

FROM friend f1

INNER JOIN friend f2

ON f1.id = f2.boss;

Howabout:SELECT f1.name,

(SELECT name FROM friend WHERE f1.boss = id) AS boss

FROM friend f1;

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Subqueries vs. Joins (2)

InnerJoin Subquery

SELECT title

FROM job_listings jl

INNER JOIN job_current jc

ON jl.title = jc.title;

Howabout:SELECT title

FROM job_listings

WHERE title IN

(SELECT title from job_current);

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Database management

Defensive databaseAvoid entering wrong data

Stop concurrent operation on the same data

at the same time

CHECK constraints and views both help maintaincontrol when you have multiple users

Limit authority to allow operate on part of

data

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CHECK CONSTRAINT Constraint

Is a restriction on what you can insert into a columnExample: NOT NULL, PRIMARY KEY, FOREIGN KEY, UNIQUE

CHECKCREATE TABLE table_name (

Column_name type CHECK (column_name IN (F, M))

Condition can be any);

ORALTER TABLE table_name

ADD CONSTRAINT CHECK column_name IN () ; condition

CHECK constraint restricts what values you can insert into a columnTry to INSERT INTO wrong data will get a error and nothing be inserted

Use the same conditions as a WHERE clause, such as AND, OR, IN,

NOT, BETWEEN, but not subquery

CHECK doesnt enforce data integrity in MySQLCan create table with check, but MySQL wont do anything and just ignores

it.

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View (1)

View

Is basically a table that only exists when you use view in

query

Virtual table

Can turn any query as a SELECT into a view

View can do more than SELECT data from tables,also can UPDATE, INSERT, DELETE

Benefits

Keep change database structure from breaking the

applications that depend on the tablesMake easier by simplifying the complex query into a simple

command

Create view to hide information that isnt needed by the use

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View (2) Create a view

CREATE VIEW view_name ASConditions Allthe queries youwanttodo

;

Use the viewSELECT * FROM view_name;

Actually viewdo allthe job ofthe queries youdefinedwhenithas beencreated

Delete viewDROP VIEW view_name;

Different RDBMSs has different behaviors

Best drop views before drop the table it is based on

MySQL wont let you drop views without its base table isexisting, but you can drop table which has view

Check structureDESC view_name;

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View (3)

CHECK OPTIONCREATE VIEW view_name AS

WHERE Conditions

WITH CHECK OPTION;

Force all inserts and updates to satisfy the

WHERE clause in the view

MySQL use CHECK OPTION to imitate

the CH

ECK CONSTRAINTIf the update/insert data is not according the

condition of view, it will show error

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View (4)

Updatable viewAn updatable view includes all the NOT NULL

columns from the table it references

Allow this kind of view to do the INSERT, UPDATE,DELETE due to all the NOT NULL column can be

touched via the view Non-updatable view

doesnt include all the NOT NULL columns

Only can do is SELECT

CANNOT update views that containsaggregate operatorsSUM, COUNT and AVG

BETWEEN, HAVING, IN, and NOT IN

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ACID

A: ATOMICITYAll the pieces of transaction must be completed or

none of them be completed.

C: CONSISTENCYKeep database in a consistent state at the end of

transaction.

I: ISOLATIONEvery transaction has a consistent view of the

database regardless of other transaction take placeat the same time.

D: DURABILITYAfter transaction, the database needs to save thedata correctly and protect it from power outages orother threats.

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Transaction (1)

Transaction is a set of SQL statementsto accomplish a single unit of work

During a transaction, if all the steps

cant be completed without interference,

none of them should be completed.

Avoid concurrent problem

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Transaction (2)

START TRANSACTION;START TRANSACTION keeps track of all the SQL

COMMIT;Make the actions permanent

ROLLBACK;Reverse everything to the way it was before youSTART TRANSACTION

No change will occur to the database untilyou COMMIT

RDBMS keep record of everything that hasbeen done when you inside a transactionIt cost storage space

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Storage engines

Make sure your storage engine is eitherBDB or InnoDB,

BDB, InnoDB are two possible way that

support transaction

RDBMS can store data behind the scenes.

Change storage engine

ALTER TABLE table_name TYPE = InnoDB;

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Root user account ROOT user

The first user ROOT user has complete control overeverything in the database.

Set passwordSET PASSWORD FOR

root @ localhost

= PASSWORD(password);ORACLE use:

ALTER user root IDENTIFIED BY new_password; Root users user name: root

localhost indicates that this is where the SQL software isinstalled and running

localhost is the default value, and it is optional

Remote accessYou have to tell the query: IP address, or a hostname instead

of localhost. [email protected]

C

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Create new user

SQL doesnt specify how to manageusers

Need check RDBMSs documentation

Most use statements:

CREATE USER user_name

IDENTIFIED BY user_password;

GRANT (1)

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GRANT (1) Control exactly what users can do to tables

and columns Typical

GRANT SELECT Can change to INSERT, DELETE, UPDATE

ON table_name

TO user_name;

Give multiple privilegeGRANT SELECT, INSERT

ON table_name

TO user_name; Name multiple users

GRANT DELETE

ON table_name

TO user1, user2;

GRANT (2)

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GRANT (2)

Assign ALL privilegesGRANT ALLON table_name

TO user_name;

Allow all permission with SELECT, INSERT,DELETE, UPDATE

Allow current user gives this privilegeto any other user

GRANT SELECTON table_name

TO user_name WITH GRANT OPTION

GRANT (3)

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GRANT (3)

Specific column: only can used for SELECT

GRANT SELECT (column_name, column_name 2)

ON table_name

TO user_name

Wildcard: Give the user the privilege for everytable in the database

GRANT SELECT

ON database_name.*

TO user_name

GRANT global privileges in MySQL

GRANT SELECT ON *.*

TO user_name;

REVOKE (1)

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REVOKE (1)

REVOKE privilegesREVOKE SELECT

ON table_name

FROM user_name;

If the unassigned privilege with get an error

Revoke GRANT OPTION privilege: Withoutremove the privilege on current user, justremove the GRANT OPTION privilegeREVOKE GRANT OPTION

ON DELETE

ON table_nameFROM user_name;

CAN NOT assign this privilege to others any more

But, all the usergot the privilege from this user, willlose their permission as well

REVOKE (2)

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REVOKE (2)

CASCADE: Remove the privilege from currentuser as well as anyone else that current usergave permission to. (usually is default)REVOKE DELETE

ON table_name

FROM user_name CASCADE;

RESTRICT: both current user and thesub_user can retain the privilege, the root getan error, if the current user gave any otheruser this privilege before

REVOKE DELETEON table_name

FROM user_name RESTRICT;

REVOKE (3)

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REVOKE (3)

If the user get the privilege fromdifferent time/people

Different RDBMSs have different response

Some will pay attention to where GRANT

came from when CASCADE is used

Some will ignore it

Just check the documentation

Both GRANT, REVOKE can use on VIEW,but be careful with the non-updatable

view

R l (1)

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Role (1)

There is no ROLE in MySQL

To give groups the privileges instead ofassign them individually

CreateCREATE ROLE role_name;

Define roles privilegesGRANT SELECT

ON table_name

TO role_name;

Assign user to the roleGRANT role_name

TO user_name;

R l (2)

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Role (2)

Delete roleDROP ROLE role_name;

Drop a role in use, it also cut related users off

from the permissions

Revoke role from userREVOKE role_name

FROM user_name;

A user can have more than one role at a time

Need make sure do not have conflicting

permissions

Denied permission > Grant permission

R l (3)

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Role (3)

Allow the roles users to grant this roleto anyone elseGRANT role_name

TO user_name WITH ADMIN OPTION

CASCADEREVOKE role_name

FROM user_name CASCADE;

RESTRICTREVOKE role_name

FROM user_name RESTRICT;

Combine ser creation and grant

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Combine user creation and grant

GRANT SELECT ON table_name

TO user_name

IDENTIFIED BY password;

Check status

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Check status

Check current userSELECT CURRENT_USER;

root@localhost

Check current

SELECT CURRENT_DATE;

SELECT CURRENT_TIME;

Reserved words

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Reserved words

There are bunch of reserved words.When try to use single-world, you glance

through the lists to make sure

SQL has a list of non-reserved words

may become reserved in future releasesof SQL.

Special characters

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Special characters

*

()

;

,

.

_

%

!

\

+

Comparison

>

!=

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ALL

BeforeSELECT columns FROM table_name

WHERE column IN

(SELECT column FROM table_name);

ALL:Greater than ALL finds any values larger than the

biggest value in the set

SELECT columns FROM table_name

WHERE column > ALL


Less than ALL finds any values smaller than thesmallest value in the set

WHERE column < ALL

ANY

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ANY

ANY

Greater than ANY finds any values larger than

the smallest value in the set

SELECT columns FROM table_name

WHERE column >ANY(SELECT column FROM table_name);

Less than ANY finds any values smaller than

the largest value in the set

SELECT columns FROM table_nameWHERE column < ANY


SOME

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SOME

Means the things as ANY in standardSQL syntax, and in MySQL .

Check the RDBMS to confirm that it

works which way

Temporary table

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Temporary table

Temporary table exists from the time youcreate it until you drop it, oruntil the usersession endsSession means from signed in to sign out

RDBMS syntax varies greatly with this, please check

first

CREATE TEMPORARY TABLE table_name

( columns);

OR

CREATE TEMPORARY TABLE table_name

AS

SELECT * FROM permanent_table;

Numeric functions

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Numeric functions

ABS(x)

ACOS(x) ASIN(x)

ATAN(x,y)

CELL(x)

COS(x) COT(x)

EXP(x)

FLOOR(x)

FORMAT(x,y)

LN(x) LOG(x), LOG(x,y)

MOD(x,y)

PI()

POWER(x,y)

RADIANS(x)

RAND(x)

ROUND(x), ROUND(x,y)

SIGN(x)

SIN(x)

SQRT(x)

TAN(x)

TRUNCATE(x,y)

Indexing

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Indexing

Index help RDBMS speed upIf you search the column frequently

Add index

ALTER TABLE table_name

ADD INDEX (column_name);

To becontinue

Get a GUI for RDBMS

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Get a GUI for RDBMS

MySQL GUI toolshttp://dev.mysql.com/downloads/gui-tools/5.0.html

CocoaMySQLhttp://cocoamysql.sourceforge.net/

Web solution: phphMySQLhttp://www.phpmysql.net/

Navicat offer 30 days free trailhttp://www.navicat.com/

SQLyog offers a free community editionhttp://www.webyog.com/en/

To becontinue

PHP/MySQL

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PHP/MySQL

PH

P help you get data via web PHP code take all date from database

and store it in an array

To becontinue

100890_633608325477500000

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