在Oracle的PL/SQL中,所有的DML操作都被Oracle内部解析为一个cursor名为SQL的隐式游标,只是对我们透明罢了。 另外,我们前面提到的一些循环操作中的指针for 循环,都是隐式cursor。 隐式cursor示例一: CREATE TABLE zrp (str VARCHAR2(10)); insert into zrp values ('ABCDEFG'); insert into zrp values ('ABCX...
Library cache:主要作用是缓存刚刚执行过的sql语句和PL/SQL语句(如存储过程、函数、包、触发器)锁对应的执行计划、解析树、Pcode/Mcode等对象,当同样的SQL语句和PL/SQL语句再次被执行时,就可以例如已缓存再Library Cache中的那些相关对象而无需再次从头开始解析,这样就提高了这些SQL、PL/SQL语句重复执行的效率. v$s...
A cursor is a SELECT statement that is defined within the declaration section of your PLSQL code. We'll take a look at three different syntaxes for cursors. Cursor without parameters (simplest) The basic syntax for a cursor without parameters is: CURSOR cursor_name IS SELECT_statement; For ...
当然了一个这样的游标是可以被多次open进行使用的,显式cursor是静态cursor,它的作用域是全局的,但也必须明白,静态cursor也只有pl/sql代码才可以使用它。下面看一个简单的静态显式cursor的示例: declare cursor get_gsmno_cur (p_nettype in varchar2) is select gsmno from gsm_resource where nettype=p_nettype...
介绍oracle cursor(游标)之前先,介绍一下oracle的库缓存,Oracle库缓存(Library Cache)是SGA中的一块内存区域,它的主要作用是缓存刚刚执行过的SQL语句或者PL/SQL语句(比如存储过程、函数、触发器、包)所对应的执行计划、解析树、Pcode,Mcode等对象,SGA相关知识可以参考我之前笔记:https://cloud.tencent.com/developer...
PL/SQL 04 游标 cursor --游标 declare cursor 游标名字 is 查询语句; begin 其他语句; end; --游标的属性 %FOUND %NOTFOUND %ISOPEN %ROWCOUNT(当前游标的指针位移量) --FETCH的两种形式 FETCH cursor_name INTO var1, var2, …; FETCH cursor_name INTO record_var;...
This Oracle tutorial explains how to declare a cursor in Oracle / PLSQL with syntax and examples. A cursor is a SELECT statement that is defined within the declaration section of your PLSQL code.
PL/SQL Code: DECLARECURSORc_employeeISSELECTemployee_id,first_name,last_nameFROMemployees;v_employee_idemployees.employee_id%TYPE;v_first_nameemployees.first_name%TYPE;v_last_nameemployees.last_name%TYPE;BEGINOPENc_employee;FETCHc_employeeINTOv_employee_id,v_first_name,v_last_name;DBMS_OUTPUT....
A private SQL area holds information about a parsed SQL statement and other session-specific information for processing. When a server process executes SQL or PL/SQL code, the process uses the private SQL area to storebind variablevalues, query execution state information, and query execution work...
cursor_name%attributeCode language:PostgreSQL SQL dialect and PL/pgSQL(pgsql) wherecursor_nameis the name of the explicit cursor. 1) %ISOPEN This attribute isTRUEif the cursor is open orFALSEif it is not. 2) %FOUND This attribute has four values: ...