table of Contents

One: the basic knowledge of mysql

Two: mysql user related commands

Three: create update delete data table

3.1 Create a table

3.2 Update table

3.3 Delete table

Four. Insert, update, delete data

4.1 Data Insertion

4.2 Update data

4.3 Delete data

Note: This article is a summary of the study of sql must know must know (fifth edition), the specific database used is mysql.

This article mainly summarizes the basic knowledge of mysql, user-related commands, creating, updating, and deleting tables.

One: the basic knowledge of mysql

1) Database: Store an organized database.

2) Table: A list of results of specific types of data.

The data stored in the table is a type of data or a list of data

3) Primary key:

Each row in the table should have a column that can uniquely identify itself, and the value in a column that can uniquely identify each row in the table .

The design table should always be designed with a primary key. The conditions for setting the primary key to hide are:

No two rows have the same primary key value
Each row must have a primary key value (the primary key value column is not allowed to be null)
The value in the primary key column is not allowed to be modified and updated
The primary key value cannot be reused.

Two: mysql user related commands

1) Enter the database:

mysql -u root -p
接着按照提示输入密码即可登陆成功

2) Modify the mysql password

$ mysql -u root
mysql> USE mysql;
mysql> UPDATE user SET authentication_string=PASSWORD("NEWPASSWORD") WHERE User='root';

3) Create, query, delete users

// 创建
mysql> CREATE USER 'test1'@'localhost' identified by '1234567';
Query OK, 0 rows affected (0.00 sec)
//查询
mysql> SELECT USER FROM mysql.user; 查询所有用户
mysql> SHOW GRANTS For [email protected]'localhost'; 查询具体某个用户
//删除
mysql> DROP USER 'test1'@'localhost';
Query OK, 0 rows affected (0.01 sec)

Three: create update delete data table

3.1 Create a table

You can use interactive tools to operate, here is mainly to explain the use of mysql statement to create

Use the create table table name to create a table

The following information is required:

The name of the new table, after the keyword CREATE TABLE
The names and definitions of the table columns are separated by commas.
Whether the column can be null

3.2 Create all the data tables required by the book "SQL Must Know and Know"


CREATE TABLE Customers
(
  cust_id      char(10)  NOT NULL ,
  cust_name    char(50)  NOT NULL ,
  cust_address char(50)  NULL ,
  cust_city    char(50)  NULL ,
  cust_state   char(5)   NULL ,
  cust_zip     char(10)  NULL ,
  cust_country char(50)  NULL ,
  cust_contact char(50)  NULL ,
  cust_email   char(255) NULL 
);

-- -----------------------
-- Create OrderItems table
-- -----------------------
CREATE TABLE OrderItems
(
  order_num  int          NOT NULL ,
  order_item int          NOT NULL ,
  prod_id    char(10)     NOT NULL ,
  quantity   int          NOT NULL ,
  item_price decimal(8,2) NOT NULL 
);


-- -------------------
-- Create Orders table
-- -------------------
CREATE TABLE Orders
(
  order_num  int      NOT NULL ,
  order_date datetime NOT NULL ,
  cust_id    char(10) NOT NULL 
);

-- ---------------------
-- Create Products table
-- ---------------------
CREATE TABLE Products
(
  prod_id    char(10)      NOT NULL ,
  vend_id    char(10)      NOT NULL ,
  prod_name  char(255)     NOT NULL ,
  prod_price decimal(8,2)  NOT NULL ,
  prod_desc  text          NULL 
);

-- --------------------
-- Create Vendors table
-- --------------------
CREATE TABLE Vendors
(
  vend_id      char(10) NOT NULL ,
  vend_name    char(50) NOT NULL ,
  vend_address char(50) NULL ,
  vend_city    char(50) NULL ,
  vend_state   char(5)  NULL ,
  vend_zip     char(10) NULL ,
  vend_country char(50) NULL 
);


-- -------------------
-- Define primary keys
-- -------------------
ALTER TABLE Customers ADD PRIMARY KEY (cust_id);
ALTER TABLE OrderItems ADD PRIMARY KEY (order_num, order_item);
ALTER TABLE Orders ADD PRIMARY KEY (order_num);
ALTER TABLE Products ADD PRIMARY KEY (prod_id);
ALTER TABLE Vendors ADD PRIMARY KEY (vend_id);


-- -------------------
-- Define foreign keys
-- -------------------
ALTER TABLE OrderItems ADD CONSTRAINT FK_OrderItems_Orders FOREIGN KEY (order_num) REFERENCES Orders (order_num);
ALTER TABLE OrderItems ADD CONSTRAINT FK_OrderItems_Products FOREIGN KEY (prod_id) REFERENCES Products (prod_id);
ALTER TABLE Orders ADD CONSTRAINT FK_Orders_Customers FOREIGN KEY (cust_id) REFERENCES Customers (cust_id);
ALTER TABLE Products ADD CONSTRAINT FK_Products_Vendors FOREIGN KEY (vend_id) REFERENCES Vendors (vend_id);

format:

create table name{

Column name one data type can be null

}

[Note]: Only columns that do not allow null values can be used as primary keys, and columns that allow null values cannot be used as unique identifiers.

3.2 Update table

Use ALTER TABLE sentences to update content, but there are a few places to pay attention to

The data contained in the table does not need to be updated.
All DBMS allow tables to add columns
Many DBMSs do not allow deleting and updating columns
The surface to be changed is given after ALTER TABLE.
List of changes made

#Add a column to the Vendors table, the data type is CHAR

ALTER TABLE Vendors
ADD vend_phone CHAR(20);

# Delete the vendor_phone column of the Vendors table

ALTER TABLE Vendors
DROP COLUMN vend_phone;

3.3 Delete table

drop table + table name

DROP TABLE CustCopy;

Four. Insert, update, delete data

4.1 Data Insertion

Use insert into ...... values statement for data insertion

insert is used to insert (add) rows to the database, corresponding to the following three situations.

Insert a complete line
Insert part of the row
Insert some query results

1) Insert a complete line

# Write SQL statements that depend on a specific column order. This sometimes makes mistakes, but it is easy to write.

INSERT INTO Customers
VALUES('1000000006',
     'Toy Land',
     '123 Any Street',
     'New York',
     'NY',
     '11111',
     'USA',
     NULL,
     NULL);

The above method is generally not recommended, we generally use the specified order to insert data, that is, specify the column name, specify the data

INSERT INTO Customers(cust_id,
     cust_contact,
     cust_email,
     cust_name,
     cust_address,
     cust_city,
     cust_state,
     cust_zip)
     VALUES('1000000009',
     NULL,
     NULL,
     'Toy Land',
     '123 Any Street',
     'New York',
     'NY',
     '11111');

2) Insert some rows

Specify a column to provide a value, the other does not provide a value.

INSERT INTO Customers(cust_id,
     cust_contact,
     cust_email,
     cust_name,
     cust_address,
    )
     VALUES('1000000009',
     NULL,
     NULL,
     'Toy Land',
     '123 Any Street'     
     );

3) Insert some query results

INSERT INTO CustomersNew(cust_id,
    cust_contact,
    cust_email,
    cust_name,
    cust_address,
    cust_city,
    cust_state,
    cust_zip,
    cust_country)
    SELECT cust_id,
    cust_contact,
    cust_email,
    cust_name,
    cust_address,
    cust_city,
    cust_state,
    cust_zip,
    cust_country
    FROM Customers;

Role: CustomersNewImport all dataCustomers

【注意】：没有使用values关键字

补充：此处将我们后面需要用到的Customers,Orders,ItemOrders，vendors,Products插入数据的代码呈现出来


INSERT INTO Customers(cust_id, cust_name, cust_address, cust_city, cust_state, cust_zip, cust_country, cust_contact, cust_email)
VALUES('1000000001', 'Village Toys', '200 Maple Lane', 'Detroit', 'MI', '44444', 'USA', 'John Smith', '[email protected]');
INSERT INTO Customers(cust_id, cust_name, cust_address, cust_city, cust_state, cust_zip, cust_country, cust_contact)
VALUES('1000000002', 'Kids Place', '333 South Lake Drive', 'Columbus', 'OH', '43333', 'USA', 'Michelle Green');
INSERT INTO Customers(cust_id, cust_name, cust_address, cust_city, cust_state, cust_zip, cust_country, cust_contact, cust_email)
VALUES('1000000003', 'Fun4All', '1 Sunny Place', 'Muncie', 'IN', '42222', 'USA', 'Jim Jones', '[email protected]');
INSERT INTO Customers(cust_id, cust_name, cust_address, cust_city, cust_state, cust_zip, cust_country, cust_contact, cust_email)
VALUES('1000000004', 'Fun4All', '829 Riverside Drive', 'Phoenix', 'AZ', '88888', 'USA', 'Denise L. Stephens', '[email protected]');
INSERT INTO Customers(cust_id, cust_name, cust_address, cust_city, cust_state, cust_zip, cust_country, cust_contact)
VALUES('1000000005', 'The Toy Store', '4545 53rd Street', 'Chicago', 'IL', '54545', 'USA', 'Kim Howard');

-- ----------------------
-- Populate Vendors table
-- ----------------------
INSERT INTO Vendors(vend_id, vend_name, vend_address, vend_city, vend_state, vend_zip, vend_country)
VALUES('BRS01','Bears R Us','123 Main Street','Bear Town','MI','44444', 'USA');
INSERT INTO Vendors(vend_id, vend_name, vend_address, vend_city, vend_state, vend_zip, vend_country)
VALUES('BRE02','Bear Emporium','500 Park Street','Anytown','OH','44333', 'USA');
INSERT INTO Vendors(vend_id, vend_name, vend_address, vend_city, vend_state, vend_zip, vend_country)
VALUES('DLL01','Doll House Inc.','555 High Street','Dollsville','CA','99999', 'USA');
INSERT INTO Vendors(vend_id, vend_name, vend_address, vend_city, vend_state, vend_zip, vend_country)
VALUES('FRB01','Furball Inc.','1000 5th Avenue','New York','NY','11111', 'USA');
INSERT INTO Vendors(vend_id, vend_name, vend_address, vend_city, vend_state, vend_zip, vend_country)
VALUES('FNG01','Fun and Games','42 Galaxy Road','London', NULL,'N16 6PS', 'England');
INSERT INTO Vendors(vend_id, vend_name, vend_address, vend_city, vend_state, vend_zip, vend_country)
VALUES('JTS01','Jouets et ours','1 Rue Amusement','Paris', NULL,'45678', 'France');

-- -----------------------
-- Populate Products table
-- -----------------------
INSERT INTO Products(prod_id, vend_id, prod_name, prod_price, prod_desc)
VALUES('BR01', 'BRS01', '8 inch teddy bear', 5.99, '8 inch teddy bear, comes with cap and jacket');
INSERT INTO Products(prod_id, vend_id, prod_name, prod_price, prod_desc)
VALUES('BR02', 'BRS01', '12 inch teddy bear', 8.99, '12 inch teddy bear, comes with cap and jacket');
INSERT INTO Products(prod_id, vend_id, prod_name, prod_price, prod_desc)
VALUES('BR03', 'BRS01', '18 inch teddy bear', 11.99, '18 inch teddy bear, comes with cap and jacket');
INSERT INTO Products(prod_id, vend_id, prod_name, prod_price, prod_desc)
VALUES('BNBG01', 'DLL01', 'Fish bean bag toy', 3.49, 'Fish bean bag toy, complete with bean bag worms with which to feed it');
INSERT INTO Products(prod_id, vend_id, prod_name, prod_price, prod_desc)
VALUES('BNBG02', 'DLL01', 'Bird bean bag toy', 3.49, 'Bird bean bag toy, eggs are not included');
INSERT INTO Products(prod_id, vend_id, prod_name, prod_price, prod_desc)
VALUES('BNBG03', 'DLL01', 'Rabbit bean bag toy', 3.49, 'Rabbit bean bag toy, comes with bean bag carrots');
INSERT INTO Products(prod_id, vend_id, prod_name, prod_price, prod_desc)
VALUES('RGAN01', 'DLL01', 'Raggedy Ann', 4.99, '18 inch Raggedy Ann doll');
INSERT INTO Products(prod_id, vend_id, prod_name, prod_price, prod_desc)
VALUES('RYL01', 'FNG01', 'King doll', 9.49, '12 inch king doll with royal garments and crown');
INSERT INTO Products(prod_id, vend_id, prod_name, prod_price, prod_desc)
VALUES('RYL02', 'FNG01', 'Queen doll', 9.49, '12 inch queen doll with royal garments and crown');

-- ---------------------
-- Populate Orders table
-- ---------------------
INSERT INTO Orders(order_num, order_date, cust_id)
VALUES(20005, '2020-05-01', '1000000001');
INSERT INTO Orders(order_num, order_date, cust_id)
VALUES(20006, '2020-01-12', '1000000003');
INSERT INTO Orders(order_num, order_date, cust_id)
VALUES(20007, '2020-01-30', '1000000004');
INSERT INTO Orders(order_num, order_date, cust_id)
VALUES(20008, '2020-02-03', '1000000005');
INSERT INTO Orders(order_num, order_date, cust_id)
VALUES(20009, '2020-02-08', '1000000001');

-- -------------------------
-- Populate OrderItems table
-- -------------------------
INSERT INTO OrderItems(order_num, order_item, prod_id, quantity, item_price)
VALUES(20005, 1, 'BR01', 100, 5.49);
INSERT INTO OrderItems(order_num, order_item, prod_id, quantity, item_price)
VALUES(20005, 2, 'BR03', 100, 10.99);
INSERT INTO OrderItems(order_num, order_item, prod_id, quantity, item_price)
VALUES(20006, 1, 'BR01', 20, 5.99);
INSERT INTO OrderItems(order_num, order_item, prod_id, quantity, item_price)
VALUES(20006, 2, 'BR02', 10, 8.99);
INSERT INTO OrderItems(order_num, order_item, prod_id, quantity, item_price)
VALUES(20006, 3, 'BR03', 10, 11.99);
INSERT INTO OrderItems(order_num, order_item, prod_id, quantity, item_price)
VALUES(20007, 1, 'BR03', 50, 11.49);
INSERT INTO OrderItems(order_num, order_item, prod_id, quantity, item_price)
VALUES(20007, 2, 'BNBG01', 100, 2.99);
INSERT INTO OrderItems(order_num, order_item, prod_id, quantity, item_price)
VALUES(20007, 3, 'BNBG02', 100, 2.99);
INSERT INTO OrderItems(order_num, order_item, prod_id, quantity, item_price)
VALUES(20007, 4, 'BNBG03', 100, 2.99);
INSERT INTO OrderItems(order_num, order_item, prod_id, quantity, item_price)
VALUES(20007, 5, 'RGAN01', 50, 4.49);
INSERT INTO OrderItems(order_num, order_item, prod_id, quantity, item_price)
VALUES(20008, 1, 'RGAN01', 5, 4.99);
INSERT INTO OrderItems(order_num, order_item, prod_id, quantity, item_price)
VALUES(20008, 2, 'BR03', 5, 11.99);
INSERT INTO OrderItems(order_num, order_item, prod_id, quantity, item_price)
VALUES(20008, 3, 'BNBG01', 10, 3.49);
INSERT INTO OrderItems(order_num, order_item, prod_id, quantity, item_price)
VALUES(20008, 4, 'BNBG02', 10, 3.49);
INSERT INTO OrderItems(order_num, order_item, prod_id, quantity, item_price)
VALUES(20008, 5, 'BNBG03', 10, 3.49);
INSERT INTO OrderItems(order_num, order_item, prod_id, quantity, item_price)
VALUES(20009, 1, 'BNBG01', 250, 2.49);
INSERT INTO OrderItems(order_num, order_item, prod_id, quantity, item_price)
VALUES(20009, 2, 'BNBG02', 250, 2.49);
INSERT INTO OrderItems(order_num, order_item, prod_id, quantity, item_price)
VALUES(20009, 3, 'BNBG03', 250, 2.49);

4.2 Update data

Use update....set statement

UPDATE Customers
SET cust_email = '[email protected]'
WHERE cust_id = '1000000005';

4.3 Delete data

DELETE FROM Customers 
WHERE cust_id = '1000000009';

Used to delete the specified data in the table

Supplement: the principle of update and deletion

Both UPDATE and DELETE statements have a WHERE clause. If the WHERE clause is omitted, it will be applied to all rows, so unless all rows are updated
Ensure that each table has a primary key, and WHERE is applied to the primary key.
Before using UPDATE and DELETE statements, first SELECT to test to ensure that the WHERE clauses are written correctly.
Use an enforced referential integrity database to prevent accidental deletion of rows.
Now MYSQL does not have UPDATE or DELETE clauses with WHERE clauses.

sql must know must know (fifth edition) learning summary (1) - mysql preliminary knowledge summary

One: the basic knowledge of mysql

Two: mysql user related commands

Three: create update delete data table

3.1 Create a table

3.2 Update table

3.3 Delete table

Four. Insert, update, delete data

4.1 Data Insertion

4.2 Update data

4.3 Delete data

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