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Click 例如:BSELECT employee_id job_idFROM employeesUNIONSELECT employee_id job_idFROM job_history显示所有曾经从事过与现在相同工作的雇员的雇员ID和职务 employee_idjob_idFROM employeesMINUSSELECT employee_idjob_idFROM job_
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Click USERreply ofA USER is receiver of a MESSAGEreceiver ofUSERwritten byMESSAGEOne or more:filed inRelationship Typesm:11:1 Relationships RolesDRAFTlocated inliving inEasy modelFewer tablesNo joinNA
Click 函数单行函数通用大小写控制函数HelloWorldHello1062400024000elloWorld132在日期上加上或减去一个数字结果仍为日期两个日期相减返回日期之间相差的天数可以用数字除24来向日期中加上或减去小时TRUNC ADD_MONTHS (11-JAN-946)TRUNC(SYSDATE YEAR) 01-JAN-95源数据类型表达式计算中 Oracl
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输入多行函数字符函数这类函数改变字符的大小写CONCAT(Hello World)SUBSTR(HelloWorld15)LENGTH(HelloWorld)INSTR(HelloWorld W)LPAD(salary10)RPAD(salary 10 )TRIM(H FROM HelloWorld)3DUAL 是一个伪表可以用来测试函数和表达式3日期日期的数学运算TRUNC MONTHS_BET
Click 参数1单行函数字符函数LOWER(SQL Course)UPPER(SQL Course)INITCAP(SQL Course)结果31SELECT last_name salary MOD(salary 5000)FROM employeesWHERE job_id = SA_REPSELECT last_name (SYSDATE-hire_date)7 AS WEEKSFR
结束本节课后应当完成如下的目标:写一个多列的子查询描述和解释当子查询查到空值时其处理方法是什么在FROM子句中写一个子查询从多行多列返回值SQL> SELECT ordid prodid qty 2 FROM item 3 WHERE prodid IN (SELECT prodid 4 FROM item 5
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