LEFT JOIN返回左表的全部行和右表满足ON条件的行,如果左表的行在右表中没有匹配,那么这一行右表中对应数据用NULL代替。 LEFT JOIN 语法 代码语言:javascript 复制 selectcolumn_name(s)from table1LEFTJOINtable2ONtable1.column_name=table2.column_name 注释:在某些数据库中,LEFT JOIN 称为LEFT OUTER JOIN L...
利用下列SQL语句在左边的窗口Schema SQL中创建上述实例中所使用的数据库 CREATETABLECustomers(idINT,CustomerNamevarchar(255),Cityvarchar(255),PetIDINT);INSERTINTOCustomersVALUES(1,"David Horn","New York",002);INSERTINTOCustomersVALUES(2,"Michael Black","Berlin",003);INSERTINTOCustomersVALUES(3,"Simon ...
CREATETABLE客户表(idINT,客户姓名varchar(255),城市varchar(255),宠物IDINT);INSERTINTO客户表VALUES(1,"张立","New York",002);INSERTINTO客户表VALUES(2,"王风","Berlin",003);INSERTINTO客户表VALUES(3,"李菊","London",001);INSERTINTO客户表VALUES(4,"赵明","Peking",Null);CREATETABLE宠物表(idINT...
Query OK, 1 row affected (0.11 sec) mysql> insert into tbl_emp(name,deptId) values('tom',1); Query OK, 1 row affected (0.08 sec) mysql> insert into tbl_emp(name,deptId) values('alice',2); Query OK, 1 row affected (0.08 sec) mysql> insert into tbl_emp(name,deptId) values('j...
‘AS’, and then in parentheses the complex query we want to use as the basis for the CTE. Right after that we can enter the query to be carried out using the name that we have given to the CTE as if it were another table. ...
Warning: In PDQ Inventory, ‘SELECT *’ throws a syntax error when joining the Computers and ComputerScans table because there is more than one column in each table with matching names. Therefore, only specific columns are referenced in the query and executed in the result set. Wrapping up Wa...
Query OK, 1 row affected (0.07 sec) mysql> INSERT INTO tbl_dept(deptName,locAdd) VALUES('美工部',12); Query OK, 1 row affected (0.08 sec) mysql> INSERT INTO tbl_dept(deptName,locAdd) VALUES('总裁办',13); Query OK, 1 row affected (0.06 sec) ...
Right join user as u on u.room_id = r.room_id and r.room_name='room of boy' Full join 1:user在左边 Select * from user Full join room 2:Room在左边 Select * From room full join user 注意:SQL错误码1054表示没有找到对应的字段名;错误码1064表示用户输入的SQL语句有语法错误 ...
ORACLE的SQL JOIN方式大全 ORACLE的SQL JOIN方式大全 在ORACLE数据库中,表与表之间的SQL JOIN方式有多种(不仅表与表,还可以表与视图、物化视图等联结),官方的解释如下所示 A join is a query that combines rows from two or more tables, views, or materialized views. Oracle Database performs a join ...
SQL是Structured Query Language的缩写，意思是结构化查询语言，是一种在数据库管理系统（RelationalDatabase Management System, RDBMS）中查询数据，或通过RDBMS对数据库中的数据进行更改的语言。看不懂。。。能不能说人话？好嘞，SQL就是一种对数据库中的数据表或者数据进行增、删、改、查等操作的语言。什么是数据...