15

SQL Structured Query Language, . SQL , , .

SQL- : , . ( ), SQL.

 SQL-

SELECT FROM

SELECT , . , SQL . 3 , Student ( SELECT FROM) . ID (studentID), (FirstName) (LastName) . (FullName).

SELECT studentID, FirstName, LastName, FirstName + ' ' + LastName AS FullName
FROM student;

:

+-----------+-------------------+------------+------------------------+
| studentID | FirstName         | LastName   | FullName               |
+-----------+-------------------+------------+------------------------+
|         1 | Monique           | Davis      | Monique Davis          |
|         2 | Teri              | Gutierrez  | Teri Gutierrez         |
|         3 | Spencer           | Pautier    | Spencer Pautier        |
|         4 | Louis             | Ramsey     | Louis Ramsey           |
|         5 | Alvin             | Greene     | Alvin Greene           |
|         6 | Sophie            | Freeman    | Sophie Freeman         |
|         7 | Edgar Frank "Ted" | Codd       | Edgar Frank "Ted" Codd |
|         8 | Donald D.         | Chamberlin | Donald D. Chamberlin   |
|         9 | Raymond F.        | Boyce      | Raymond F. Boyce       |
+-----------+-------------------+------------+------------------------+
9 rows in set (0.00 sec)    

CREATE TABLE

CREATE TABLE . , .

CREATE TABLE table_name (
    column_1 datatype,
    column_2 datatype,
    column_3 datatype
);

ALTER TABLE

ALTER TABLE . :

ALTER TABLE table_name
ADD column_name datatype;

CHECK

CHECK , .

CHECK , , . CHECK , .

Persons CHECK (Age). , 18 .

CREATE TABLE Persons (
    ID int NOT NULL,
    LastName varchar(255) NOT NULL,
    FirstName varchar(255),
    Age int,
    CHECK (Age>=18)
);

CHECK CHECK :

CREATE TABLE Persons (
    ID int NOT NULL,
    LastName varchar(255) NOT NULL,
    FirstName varchar(255),
    Age int,
    City varchar(255),
    CONSTRAINT CHK_Person CHECK (Age>=18 AND City='Sandnes')
);    

WHERE (AND, OR, IN, BETWEEN LIKE)

WHERE .

, , SELECT WHERE. WHERE, 5 .

 SELECT studentID, FullName, sat_score, rcd_updated FROM student;   
+-----------+------------------------+-----------+---------------------+
| studentID | FullName               | sat_score | rcd_updated         |
+-----------+------------------------+-----------+---------------------+
|         1 | Monique Davis          |       400 | 2017-08-16 15:34:50 |
|         2 | Teri Gutierrez         |       800 | 2017-08-16 15:34:50 |
|         3 | Spencer Pautier        |      1000 | 2017-08-16 15:34:50 |
|         4 | Louis Ramsey           |      1200 | 2017-08-16 15:34:50 |
|         5 | Alvin Greene           |      1200 | 2017-08-16 15:34:50 |
|         6 | Sophie Freeman         |      1200 | 2017-08-16 15:34:50 |
|         7 | Edgar Frank "Ted" Codd |      2400 | 2017-08-16 15:35:33 |
|         8 | Donald D. Chamberlin   |      2400 | 2017-08-16 15:35:33 |
|         9 | Raymond F. Boyce       |      2400 | 2017-08-16 15:35:33 |
+-----------+------------------------+-----------+---------------------+
9 rows in set (0.00 sec)

SELECT, WHERE.

STUDENT studentID, FullName, sat_score, recordUpdated
FROM student
WHERE (studentID BETWEEN 1 AND 5 OR studentID = 8)
        AND
        sat_score NOT IN (1000, 1400);
+-----------+----------------------+-----------+---------------------+
| studentID | FullName             | sat_score | rcd_updated         |
+-----------+----------------------+-----------+---------------------+
|         1 | Monique Davis        |       400 | 2017-08-16 15:34:50 |
|         2 | Teri Gutierrez       |       800 | 2017-08-16 15:34:50 |
|         4 | Louis Ramsey         |      1200 | 2017-08-16 15:34:50 |
|         5 | Alvin Greene         |      1200 | 2017-08-16 15:34:50 |
|         8 | Donald D. Chamberlin |      2400 | 2017-08-16 15:35:33 |
+-----------+----------------------+-----------+---------------------+
5 rows in set (0.00 sec)    

UPDATE

UPDATE.

WHERE , . . :

UPDATE table_name
SET column1 = value1, 
    column2 = value2, ...
WHERE condition;

( Name) Id 4:

UPDATE Person
SET Name = Elton John
WHERE Id = 4;

, . , JOIN. :

UPDATE table_name1
SET table_name1.column1 = table_name2.columnA
    table_name1.column2 = table_name2.columnB
FROM table_name1
JOIN table_name2 ON table_name1.ForeignKey = table_name2.Key

(Manager) :

UPDATE Person
SET Person.Manager = Department.Manager
FROM Person
JOIN Department ON Person.DepartmentID = Department.ID    

GROUP BY

GROUP BY .

GROUP BY:

SELECT column_name, COUNT(*)
FROM table_name
GROUP BY column_name;

HAVING

HAVING , GROUP BY. , .

HAVING:

SELECT column_name, COUNT(*)
FROM table_name
GROUP BY column_name
HAVING COUNT(*) > value;    

AVG()

AVG, , , SQL.

:

SELECT groupingField, AVG(num_field)
FROM table1
GROUP BY groupingField    

Student:

SELECT studentID, FullName, AVG(sat_score) 
FROM student 
GROUP BY studentID, FullName;    

AS

AS .

SELECT user_only_num1 AS AgeOfServer, (user_only_num1 - warranty_period) AS NonWarrantyPeriod FROM server_table

.

+-------------+------------------------+
| AgeOfServer | NonWarrantyPeriod      | 
+-------------+------------------------+
|         36  |                     24 |
|         24  |                     12 | 
|         61  |                     49 |
|         12  |                      0 | 
|          6  |                     -6 |
|          0  |                    -12 | 
|         36  |                     24 |
|         36  |                     24 | 
|         24  |                     12 | 
+-------------+------------------------+

, AS JOIN.

SELECT ord.product, ord.ord_number, ord.price, cust.cust_name, cust.cust_number FROM customer_table AS cust

JOIN order_table AS ord ON cust.cust_number = ord.cust_number    

.

+-------------+------------+-----------+-----------------+--------------+
| product     | ord_number | price     | cust_name       | cust_number  |
+-------------+------------+-----------+-----------------+--------------+
|     RAM     |   12345    |       124 | John Smith      |  20          |
|     CPU     |   12346    |       212 | Mia X           |  22          |
|     USB     |   12347    |        49 | Elise Beth      |  21          |
|     Cable   |   12348    |         0 | Paul Fort       |  19          |
|     Mouse   |   12349    |        66 | Nats Back       |  15          |
|     Laptop  |   12350    |       612 | Mel S           |  36          |
|     Keyboard|   12351    |        24 | George Z        |  95          |
|     Keyboard|   12352    |        24 | Ally B          |  55          |
|     Air     |   12353    |        12 | Maria Trust     |  11          |
+-------------+------------+-----------+-----------------+--------------+    

ORDER BY

ORDER BY SELECT. (FullName) . (ASC), DESC.

SELECT studentID, FullName, sat_score
FROM student
ORDER BY FullName DESC;    

COUNT

COUNT .

COUNT:

  • ( Group by)
  • ( Group By)

SQL . , COUNT AS.

SELECT count(*) AS studentCount FROM student; 

DELETE

DELETE .

! , . WHERE , . :

DELETE FROM table_name
WHERE condition;    

Person Id 3:

DELETE FROM Person
WHERE Id = 3;    

INNER JOIN

JOIN, , , .

SELECT * FROM A x JOIN B y ON y.aId = x.Id

LEFT JOIN

LEFT JOIN . . , null.

SELECT * FROM A x LEFT JOIN B y ON y.aId = x.Id    

RIGHT JOIN

RIGHT JOIN . , , . , null.

SELECT * FROM A x RIGHT JOIN B y ON y.aId = x.Id

FULL OUTER JOIN

FULL OUTER JOIN , . , , . .

SELECT Customers.CustomerName, Orders.OrderID
FROM Customers
FULL OUTER JOIN Orders
ON Customers.CustomerID=Orders.CustomerID
ORDER BY Customers.CustomerName

INSERT

INSERT .

INSERT INTO table_name (column_1, column_2, column_3) 
VALUES (value_1, 'value_2', value_3);    

LIKE

LIKE WHERE HAVING ( GROUP BY) , .

SQL , FullName Monique Greene.

SELECT studentID, FullName, sat_score, rcd_updated
FROM student 
WHERE 
    FullName LIKE 'Monique%' OR 
    FullName LIKE '%Greene'; 
+-----------+---------------+-----------+---------------------+
| studentID | FullName      | sat_score | rcd_updated         |
+-----------+---------------+-----------+---------------------+
|         1 | Monique Davis |       400 | 2017-08-16 15:34:50 |
|         5 | Alvin Greene  |      1200 | 2017-08-16 15:34:50 |
+-----------+---------------+-----------+---------------------+
2 rows in set (0.00 sec)    

LIKE NOT, , , , . SQL , FULL NAME cer Pau Ted.

SELECT studentID, FullName, sat_score, rcd_updated
FROM student 
WHERE FullName NOT LIKE '%cer Pau%' AND FullName NOT LIKE '%"Ted"%';    
+-----------+----------------------+-----------+---------------------+
| studentID | FullName             | sat_score | rcd_updated         |
+-----------+----------------------+-----------+---------------------+
|         1 | Monique Davis        |       400 | 2017-08-16 15:34:50 |
|         2 | Teri Gutierrez       |       800 | 2017-08-16 15:34:50 |
|         4 | Louis Ramsey         |      1200 | 2017-08-16 15:34:50 |
|         5 | Alvin Greene         |      1200 | 2017-08-16 15:34:50 |
|         6 | Sophie Freeman       |      1200 | 2017-08-16 15:34:50 |
|         8 | Donald D. Chamberlin |      2400 | 2017-08-16 15:35:33 |
|         9 | Raymond F. Boyce     |      2400 | 2017-08-16 15:35:33 |
+-----------+----------------------+-----------+---------------------+
7 rows in set (0.00 sec)    

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