零基礎快速自學SQL,2天足矣!

????10????????????7?

??????????????10????

?????????????????????????????????????SQL?

SQL??? Structured Query Language???????????????????????????????????????????????????????

?? ORACLE?DB2?Sybase?SQLServer?MySQL?MS Access????????????????????????????????????????????????????????????????????????????????????????????SQL???????

????????SQL?????????????????????????????????????SQL?

???????????????????????????????????

?????????????????????????????

  • SQL??????
  • ????????
  • SQL????
  • SQL????

SQL??????

?????SQL??????????

???????????????????SQL Sever?????MySQL?????????????????????????????????2????SQL??????1?????SQL Sever?????????MySQL????????????????????????????MySQL?SQL Sever??????

????????SQL?????????????????????SQL????????????????????Excel????????????????????w3school?????????????????????

SQL????

1?????MySQL???????phpstudy????????mysql??????????????

2???????phpstudy???phpstudy?????????????????????????

3?????Navicat??

????????????????????????????SQL??

4???Navicat???????

??? ? ? ?????????????????????????????????????????????root????????phpstudy??mysql??????????root????????????????????

??????????????

5???????????????????????

6????5?????????

???4???????????????test1???????????????????????

?????????????sqltest1.sql??test1???

???????????????????????????

??????????????????????????????

7???sql?????

??????? ? ? ???????????sql????????????????????????????????

8?????

??????????????????w3c?sql??????

9?????

????sql????????????????

???sql??????????sql???????????????????????????????w3c?sql????????????????????

????????

?????????????????????????????????????????????

1?CREATE TABLE????

?????????~

???????????????????????????????????????

???????

emp?
orders?

2?INSERT(??)

???????

??????emp?
??????orders?

3?UPDATE(??)

4?DELETE(??)

???delete??emp??????????????????????????????emp?id??orders?????????emp???id?????orders??????

5?DISTINCT????

???????????????????????????????????????????distinct???????????????????

???distinct?????????????*?????????? ????????????SQL?????????????name????????????????????distinct????????.

6?Select????

SELECT ??????????????????????????????????????????????90%?

SQL SELECT ??

SELECT ??? FROM ???

???

SELECT * FROM ???

??????? ?LastName? ? ?FirstName? ????????? ?Persons? ??????????????? SELECT ???

SELECT LastName,FirstName FROM Persons

SELECT??????????????

SQL????

????SQL?????????????????????????????????????

1?AVG??

AVG ????????????NULL ?????????

2?COUNT()

COUNT( ) ????????????????

3?MAX()

MAX????????????NULL????????

4?MIN()

MIN?????????????NULL????????

5?SUM()

SUM??????????

6?ROUND()

ROUND ???????????????????

round???????

7?FORMAT()

FORMAT ???????????????

format???????

SQL????

?????????????????????SQL????????????????????

1?LIMIT

2?LIKE

????where?????????????

???????????????%??????????????????like ????????

???????????

3?IN

??????????????????

4?JOIN

?????JOIN???????????????????????????????????

??????????????primary key?????foreign key?????????

??????????????????????????INNER JOIN??

?????????????????

  • LEFT JOIN:????????????????????
  • RIGHT JOIN????????????????????
  • FULL JOIN:????????????????

5?ALTER

??????alter??????????????alter?????

6?UNION

UNION ???????????? SELECT ???????

????UNION ??? SELECT ???????????????????????????????? SELECT ?????????????

??????????????????!

UNION?UNION ALL??????????????ALL???????????

??????????????????PRIMARY KEY????????????????????????

?PRIMARY KEY????????????? UNIQUE ????????????? PRIMARY KEY ???

????UNION????????SQL???

7?AUTO-INCREMENT(??)

????????????????????????????????

8?ORDER BY

????????????order by?SQL???order by???????????????????ASC???????????

????????

  • ASC:????????
  • DESC:????????

????

ASC??

??DESC????????????????????SQL????

9?GROUP BY

????????????????????????????

????????????????

10?HAVING

????????????where???????????????having??????where??????????????

???????SQL???

????????????????

11?DEFAULT

DEFAULT?????????????

?????????????????????????????SQL?????????????????????????????????????~

??????????????????????????????????????

?????????????Facebook??????????~

?????

???????10???????

4????????????

???????5?????

???????43?Excel????????

??????Excel??????????

????????????