1.cursor 游标 (不同于select的一次性全部取出) 比如一条where语句,对应了N条结果,而对应N条结果集组成的资源,取出资源的接口/句柄,就是游标 我们沿着游标,可以一次只取一行 2.基本知识 #declare 声明游标 declare 游标名 cursor for select_statement #open 打开游标资源 open 游标名 #fetch 取值 fetch 游标名...
positionFROMemployees;DECLARECONTINUEHANDLERFORNOTFOUNDSETdone=TRUE;OPENcursor_employee;read_loop:LOOPFETCHcursor_employeeINTOemp_name,emp_position;IFdoneTHENLEAVEread_loop;ENDIF;-- 输出员工信息SELECTemp_name,emp_position;END
在MySQL中,你可以使用DECLARE CURSOR语句来声明一个游标。下面是DECLARE CURSOR的基本语法: DECLARE cursor_name CURSOR FOR SELECT column1, column2, ... FROM table_name WHERE condition; cursor_name:游标的名称,你可以自定义一个唯一的名称来标识游标。 SELECT column1, column2, ...:指定游标要使用的SQL查...
• Cursor declare语句用来声明一个游标和指定游标对应的数据集合,通常数据集合是一个select语句 • Select_statement代表一个select语句 mysql> SELECT id,name FROM teacherwhereid>=2;+---+---+ | id | name | +---+---+ |2| Li si | |3| Wang wu | |4| Liu liu | |5| Ding qi | +...
cursor close用来关闭之前打开的游标; 如果关闭一个未打开的游标,则MySQL会报错; 如果在存储过程和函数中未使用此语句关闭打开的游标,则游标会在声明的begin...end语句块执行之后自动关闭; cursor declare用来声明一个游标和指定游标对应的数据集合,通常数据集合是一个select语句。
DECLARE 是MySQL 中的一个语句,主要用于声明局部变量、条件、游标等。它通常用在存储过程(Stored Procedure)、函数(Function)或触发器(Trigger)中。 基础概念 局部变量:在存储过程或函数内部定义的变量,其作用域仅限于该存储过程或函数。 条件:用于定义存储过程中的条件逻辑。 游标:用于在存储过程中遍历结果集。 优势...
This statement declares a cursor and associates it with a SELECT statement that retrieves the rows to be traversed by the cursor. To fetch the rows later, use a FETCH statement. The number of columns retrieved by the SELECT statement must match the number of output variables specified in the...
I got this to work by putting in a stored procedure; though may examples show a cursor within a stored procedure, nowhere does it say it needs to be between a block, not even within a stored procedure, directly from a sql statement(s). I don't even know about the command window. My...
This statement declares a cursor and associates it with a SELECT statement that retrieves the rows to be traversed by the cursor. To fetch the rows later, use a FETCH statement. The number of columns retrieved by the SELECT statement must match the number of output variables specified in the...
Re: DECLARE CURSOR Posted by:pradeep kaltari Date: May 06, 2007 11:19PM Hi, You cannot declare a cursor inside a while block. You need to declare the cursor in the begining, you can open the cursor in the while block. The rows being selected in the cursor depend upon the values of...