...例如 NOT IN、IS NOT NULL、NOT EXISTS,其中 NOT IN、NOT EXISTS 用于排除数据记录,应用在WHERE子句中较多;NOT EXISTS 也应用于创建数据库、数据表中使用较多...条件判断1 CASE表达式CASE表达式是一个比较常用的表达式工具,它允许在SQL语句中使用逻辑结构为 如果 ... 那么... 如果 ... 那么... 最后 ...
Writingcaseexpressions directly in SQL statements is fine for one-off logic. Often you’ll want to reuse this logic in many queries. Copy-pasting it into every statement is error-prone and hard to maintain. You can avoid these problems by moving the logic into the table definition withvir...
resumable--enable or disable resumableforcurrentsession(DefaultFALSE)resumable_name--text string to help identify resumable statement resumable_timeout--waittime(inseconds)forRESUMABLE(Default7200)date_cache--size(inentries)ofdate conversioncache(Default1000)no_index_errors--abort load on any indexerrors...
In other words, PL/SQL raises a CASE_NOT_FOUND error if you don’t specify an ELSE clause and the result of the CASE expression does not match any value in the WHEN clauses. Note that this behavior of the CASE statement is different from the IF THEN statement. When the IF THEN state...
This Oracle WHERE clause example uses the WHERE clause to define multiple conditions, but instead of using theAND condition, it uses theOR condition. In this case, this SELECT statement would return allsupplier_idvalues where thesupplier_nameis AppleorMicrosoft. ...
You can use aCASEexpression in any statement or clause that accepts a valid expression. For example, you can use theCASEexpression in statements such asSELECT,UPDATE, orDELETE, and in clauses likeSELECT,WHERE,HAVING, andORDDER BY. OracleCASEexpression has two formats: the simpleCASEexpression ...
In this example, if the deptno column has a 10 in it, the SQL query will return the value accounting rather than the number 10. If the deptno is not 10, 20, 30, or 40, then the CASE statement will fall through to the ELSE clause, which will return unassigned. Note that with a ...
--声明游标;CURSOR cursor_name IS select_statement--For 循环游标--(1)定义游标--(2)定义游标变量--(3)使用for循环来使用这个游标 declare--类型定义 cursor c_jobisselectempno,ename,job,salfromempwherejob='MANAGER';--定义一个游标变量c_row c_job%ROWTYPE,该类型为游标c_job中的一行数据类型 ...
(2)If CURSOR_SPACE_FOR_TIMEis set to true, then a cursorcan be deallocated only when all application cursors associated with itsstatement are closed. In this case, Oracle Database need not verify thata cursor is in the cache because it cannot be deallocated while an applicationcursor associat...
For the case where one or more of your segmentsrequirevalues, you need to perform extra steps to prevent data inconsistencies. The simplest way to do this is to define your segment structures completely, navigate to your form with the new descriptive flexfield, query up each record in your ...