SQL进阶---第一单元(第四到第六课)、Manipulation

[align=center]SQL进阶---第一单元、Manipulation[/align]

第四课、MANIPULATION Create

 

MANIPULATION Create

CREATE TABLE celebs (

        id INTEGER,

        name TEXT,

        age INTEGER);

This 

CREATE

 statement
creates a new tablein the database named 

celebs

.
You can use the 

CREATE

statement
anytime you want tocreate a new table from scratch.

1. 

CREATE
TABLE

 is a clause that tells
SQL you want to create a new table. 

2. 

celebs

 is
the name of the table. 

3. 

(id INTEGER,name TEXT, age INTEGER)

 is
a list of parameters definingeach column in the table and its data type. 

id

 is
the first column in the table. It stores values of data type 

INTEGER

name

 is
the second column in the table. It stores values of data type 

TEXT

age

 is
the third column in the table. It stores values
1e2bf
of data type 

INTEGER

 

Instructions

1.Add
a row to the table. In thecode editor type

INSERTINTO
celebs(id, name, age)

                                     VALUES
(1,'Justin
Bieber',21);

        INSERT INTOcelebs(id,name,age)

                         VALUES(1,'justin Bieber',21);

        Run a query to
see results.

Database Schema

Celebs    1 rows
Id	INTEGER
Name	TEXT
Age	INTEGER

2.To
view the row you justcreated, under the INSERTstatementtype

SELECT *
FROM
celebs;

Query Results

id	name	age
1	justin Bieber	21

 

第五课、Insert

MANIPULATION Insert

INSERT INTO celebs (id, name, age) VALUES (1, 'Justin Bieber', 21);

This 

INSERT

 statement
inserts new rows intoa table. You can use the 

INSERT

 statement
when you want to addnew records.

1. 

INSERT
INTO

 is a clause that adds thespecified
row or rows. 
2. 

celebs

 is
the name of the table the rowis added to. 

3. 

(id, name,age)

 is
a parameter identifying thecolumns that data will be inserted into. 

4. 

VALUES

 is
a clause that indicates the data being inserted. 

(1, 'Justin Bieber', 21)

 is
a parameter identifying the values being inserted.

1

 is
an integer that will be inserted into the 

id

 column

'Justin Bieber'

 is
text that will be inserted into the 

name

column

21

 is
an integer that will be inserted into the 

age

 column

 

Instructions

1.Add
three more celebs to thetable. In the code editor type:

INSERTINTO
celebs(id, name, age)

                      VALUES
(2,'Beyonce
Knowles',33);

INSERTINTO
celebs(id, name, age)

                      VALUES
(3,'Jeremy
Lin',26);

INSERTINTO
celebs(id, name, age)

                      VALUES
(4,'Taylor
Swift',26);

  2.Let's
take a closer look at SELECT.
Under the INSERTstatements
type

SELECT name
FROM
celebs;

 

INSERT INTO celebs (id, name, age)

VALUES (2, 'Beyonce Knowles', 33);

 

INSERT INTO celebs (id, name, age)

VALUES (3, 'Jeremy Lin', 26);

 

INSERT INTO celebs (id, name, age)

VALUES (4, 'Taylor Swift', 26);

 

SELECT name FROM celebs;

 

Query Results

name

Justin Bieber

Beyonce Knowles

Jeremy Lin

Taylor Swift

Database Schema

Celebs       4 rows
Id	INTEGER
Name	TEXT
Age	INTEGER

 

第六课、Select

MANIPULATION  
Select

SELECT name FROM celebs;

SELECT

 statements
are used to fetchdata from a database. Here, 

SELECT

 returns
all data in the 

name

 column
of the 

celebs

 table.

1. 

SELECT

 is
a clause that indicatesthat the statement is a query. You will use 

SELECT

 every
time you query data from a database. 

2. 

name

 specifies
the column to query data from. 

3. 

FROM celebs

 specifies
the name of the table to query data from. In thisstatement, data is queried from the 

celebs

 table. 

You can also query data fromall columns in a table with 

SELECT

.

SELECT * FROM celebs;

*

 is
a special wildcardcharacter that we have been using. It allows you to select every column in atable without having to name each one individually.Here, the result set
containsevery column in the 

celebs

 table.

SELECT

 statements
always return anew table called the resultset.

 

Instructions

1.Now
that you know how to addrows to the table, let's edit a row. In the code editor type

UPDATE celebs

       SET
age = 22WHERE
id = 1;

SELECT *
FROM
celebs;

 

UPDATE celebs SET age = 22

                         WHEREid =1;

SELECT * FROM celebs;

 

Query Results

id	name	age
1	Justin Bieber	22
2	Beyonce Knowles	33
3	Jeremy Lin	26
4	Taylor Swift	26

Database Schema

Celebs     4 rows
Id	INTEGER
Name	TEXT
Age	INTEGER