SELECT 语句中的子查询子查询(Sub Query)或者说内查询(Inner Query),也可以称作嵌套查询(Nested Query),是一种嵌套在其他 SQL 查询的 WHERE 子句中的查询...使用子查询必须遵循以下几个规则: 子查询必须括在圆括号中。 子查询的 SELECT 子句中只能有一个列,除.
CASE WHEN EXISTS是Oracle SQL语句中常用的条件查询语句之一。它通常用于在满足一定条件时执行特定的操作。本文将介绍CASE WHEN EXISTS的用法及示例,帮助读者更好地理解和使用它。 CASE WHEN EXISTS语句的基本语法如下: CASE WHENEXISTS(subquery)THENexpression ELSEexpression END 在上述语法中,CASE是关键字,EXISTS子句用...
NO_DATA_FOUND 异常码 ORA-01403 SELECT INTO 语句中没有任何返回结果5，TOO_MANY_ROWS 异常码 ORA-01422 SELECT INTO 语句中返回结果6，ZERO_DIVIDE 异常码 ORA-01476 试图用0作为除数7，CURSOR_ALREADY_OPEN 异常码 ORA-06511 试图打开一个已经打开的游标
In this example, a join between a table called EMP and itself is being created to display the name of the employees' managers. A regular join in this case would probably be more efficient. Here is another example, a scalar subquery in the where clause: SELECT ename, sal, comm FROM emp ...
selects.SQL_TEXT 语句, s.SQL_FULLTEXT 完成语句, s.CPU_TIME cpu总耗时, s.ELAPSED_TIME 执行总耗时, s.EXECUTIONS 执行次数, s.FIRST_LOAD_TIME 初次加载时间, s.LAST_LOAD_TIME 最后加载时间, s.LAST_ACTIVE_TIME 最后执行时间fromv$sqlarea swheres.SQL_TEXT like'%ent_query_result%';--查看sql执...
■ A subquery in a DELETE, SELECT, or UPDATE statement ■ A query of a view or of a materialized view ■ A SELECT statement with the DISTINCT operator ■ A SELECT statement with a GROUP BY clause or ORDER BY clause ■ A SELECT statement that is combined with another SELECT statement wit...
select case when bh is null then 0 when bh=1 then 99 else bh end bhs, xh,code from chinese 一、利用 CASE 语句更新列值执行本语句将性别为男的伙食补助修改为 120,女修改为 100 UPDATE TB_EMP2 SET 伙食补助=CASE WHEN 性别='男' then 120 WHEN 性别='女' then 100 END 当列 cj 的值为 ...
selectcasewhenbhisnullthen0whenbh=1then99elsebhendbhs,xh,codefromchinese一、利用CASE语句更新列值执行本语句将性别为男的伙食补助修改为120,女修改为100UPDATETB_EMP2SET伙食补助=CASEWHEN性别='男'then120WHEN性别='女'then100END当列cj的值为74时,修改其值为80,,为97时,修改其值为100,其它值不变update...
SELECT * FROM emp_phone PIVOT ( MAX(phone) for type IN (1 as home, 2 as office, 2 as mobile) ) / PIVOT以后的字句都是新加的。但万变不离其宗,还是要用到分组函数。IN后边是按type的不同值映射成不同的列。简单吧? 列变行,这是UNPIVOT的工作,写法如下: SELECT * FROM emp_phone_x UNPIVOT...
oracleI基础入门(11)--case 2012-06-12 10:36 − CASECASE 是 SQL 用来做为 if-then-else 之类逻辑的关键字。 CASE 的语法如下:SELECT CASE ("栏位名") WHEN "条件1" THEN "结果1" WHEN "条件2" THEN "结果2"...[ELSE "结果N"]ENDFROM "表格名""条件" 可... Crazy-H 0 224 oracle...