数据分析招聘要求：熟练SQL！| 精简版复习大纲送给大家！

#语法
SELECT <Column List>
FROM <Table Name>
WHERE <Search Condition>

# 例子
SELECT FirstName, LastName, OrderDate
FROM Orders WHERE OrderDate > '10/10/2010'

#语法
SELECT DISTINCT <Column_name>
FROM <Table Name>

#例子
SELECT DISTINCT FirstName FROM Orders

#语法
SELECT <col_name >
FROM table_name 
limt 5 offset 1;

#例子
SELECT FirstName FROM Orders  limt 5 offset 1;

#语法
SELECT co_name1,col_name2 
FROM table_name 
ORDER BY col_name1 DESC,col_name2 ASC

#例子
SELECT ,FirstName
FROM Orders 
ORDER BY OrderDate DESC

#范围内检查
SELECT col_name FROM table_name WHERE col_name BETEWEEN 5 AND 10;

#空值检查
SELECT col_name FROM table_name WHERE col_name IS null;

# in操作符
SELECT col_name FROM table_name WHERE col_name IN (....);

# NOT操作符
SELECT col_name FROM table_name WHERE NOT (条件);

#AND 和 OR 注意优先级 and 优先级高于or
SELECT col_name FROM table_name 
WHERE (condi_1 OR condi_2) AND condi_3;

#第五部分使用通配符进行过滤
SELECT col_name FROM table_name WHERE col_name like '..%..';

SELECT col_name FROM table_name WHERE col_name like '.._..';

SELECT col_name FROM table_name WHERE col_name like '[]%';

#语法
SELECT <Column List>, <Aggregate Function>(<Column Name>)
FROM <Table Name>
WHERE <Search Condition>
GROUP BY <Column List>

#例子
SELECT LastName, SUM(OrderValue)
FROM Orders
WHERE OrderDate > '10/10/2010'
GROUP BY LastName

注意点： 
GROUP BY 后面也可以接条件。
WHERE 语句和HAVING配合的使用。WHERE在HAVING之前。
WHERE 过滤针对的是行，HAVING过滤针对的是组。

/*
SELECR 
FROM 
WHERE
GROUP BY 
HAVING 
ORDER BY
*/
SELECT  col_name FROM table_name
WHERE <condition_1>
GROUP BY <col_name>
HAVING <condition_2>
ORDER BY <col_name>

SELECT col_name FROM table_name 
WHERE  col_name  = 
(SELECT  col_name  FROM table_name WHERE .... );

#语法
SELECT <Column List>
FROM <Table1> JOIN <Table2>
ON <Table1>.<Column1> = <Table2>.<Column1>、

#例子
SELECT Orders.LastName, Countries.CountryName
FROM Orders INNER JOIN Countries ON
Orders.CountryID = Countries.ID

除此之外还有左联结 LEFT JOIN
右联结 RIGHT JOIN
全联结 FULL JOIN

#语法
SELECT <Column List> FROM <Table1>
UNION
SELECT <Column List> FROM <Table2>

#例子
SELECT <Column List> FROM <Table1>
UNION
SELECT <Column List> FROM <Table2>

#语法
INSERT INTO <Table Name>
(<Column List>) VALUES (<Values>)

#例子
INSERT INTO Orders
(FirstName, LastName, OrderDate) VALUES
('John', 'Smith', '10/10/2010')

#语法
UPDATE <Table Name>
SET <Column1> = <Value1>, <Column2> = <Value2>, …
WHERE <Search Condition>

#例子
UPDATE Orders
SET FirstName = 'John', LastName = 'Who' WHERE LastName='Wo'

#语法
DELETE FROM <Table Name>
WHERE <Search Condition>

#例子
DELETE FROM Orders
WHERE OrderDate < '10/10/2010'

# 语法
CREATE TABLE <Table Name>
( Column1 DataType,
 Column2 DataType,
 Column3 DataType)
 
 # 例子
 CREATE TABLE Orders
( FirstName CHAR(100),
 LastName CHAR(100),
 OrderDate DATE)

#语法
CREATE TABLE <Table Name>
ADD col_name Datatype;

CREATE TABLE <Table Name>
DROP COLUMN <col_name>
 
# 例子
ALTER TABLE Vendors 
ADD vend_phone CHAR(20); 

ALTER TABLE Vendors 
DROP COLUMN vend_phone; 

#语法
DROP TABLE table_name;

#例子
DROP TABLE CustCopy;