1 内連接配接查詢
select 字段1,字段2 from 表1,表2 where 表1.字段3=表2.字段3; //要有相同的字段3 查詢的是具有相同的字段3值 (注:表1 inner join 表2 中間的inner on一般可以省略)
例如:
原表country
mysql> select * from country;
+----+----------+------------+------+----------+
| id | name | population | area | language |
+----+----------+------------+------+----------+
| 1 | mySQL | 13 | 960 | chinese |
| 2 | American | 4 |60 | English |
| 3 | Japan | 89 | 30 | Jpanese |
| 4 | England | 2 | 300 | English |
+----+----------+------------+------+----------
原表library
mysql> select * from library;
+----+---------------+--------+-------+
| id | name | author | price |
+----+---------------+--------+-------+
| 1 | java範例大全 | 張帆 | 99 |
| 2 | mySQL | 潘凱華 | 50 |
| 3 | SQLserver2005 | 劉智勇 | 80 |
| 4 | mySQL | 李慧 | 50 |
+----+---------------+--------+-------+
mysql> select area,author from country,library where country.name=library.name;
+------+--------+
| area | author |
+------+--------+
| 960 | 潘凱華 |
| 960 | 李慧 |
+------+--------+
2 左外連接配接
mysql> select language,area,author from country left join library on country.name=library.name; //傳回的結果除内連接配接的資料外,還包括左表中不符合條件資料
+----------+------+--------+
| language | area | author |
+----------+------+--------+
| chinese | 960 | 潘凱華 |
| chinese | 960 | 李慧 |
| English | 60 | NULL |
| Jpanese | 30 | NULL |
| English | 300 | NULL |
+----------+------+--------+
3 右外連接配接
mysql> select language,area,author from country right joinlibrary on country.name=library.name; // //傳回的結果除内連接配接的資料外,還包括右表中不符合條件資料
+----------+------+--------+
| language | area | author |
+----------+------+--------+
| NULL | NULL | 張帆 |
| chinese | 960 | 潘凱華 |
| NULL | NULL | 劉智勇 |
| chinese | 960 | 李慧 |
+----------+------+--------+
4 複合條件連接配接查詢
mysql>select population,area,author,price from country,library where country.name=library.name and price>30;
5 子查詢
1 帶IN關鍵字的子查詢
mysql> select * from country wherename in(select name from library);