A detailed explanation of basic grammar of PL/SQL Programming (I.)

I. What is PL/SQL (Procedure language/sql)
Concept: Plsql is Oracle's procedural extension of SQL language
Refers to the addition of process-processing statements (such as branching, loops, and so on) in the SQL command language, enabling the SQL language to have process processing power.
The structure of PL/sql:

declare      说明部分    （变量说明，光标申明，例外说明 〕begin      语句序列   （DML语句〕… exception      例外处理语句   End;

A simple PL/SQL program
If you need to use set serveroutput on the command line to open the display first

--声明变量begin-- 程序执行的主体dbms_output.put_line(‘Hello World‘);--输出语句end;

Two. basic syntax for PL/SQL programs
1. Constants and variables

2. Variable type

3. Use of reference and record-type variables

The use of reference-type variables

-- 查询并打印7839的姓名和薪水declare   -- 定义姓名和薪水的变量  --即引用emp表中ename列的类型  psal emp.sal%type;   --即引用emp表中sal列的类型begin  -- 查询语句 赋值的两种方式 1.:=   2. into关键字  select ename,sal into pname,psal from emp where empno=‘7839‘;  dbms_output.put_line(pname ||‘的薪水是‘|| psal);end;

Record type variable

-- 查询并打印7839的姓名和薪水declare   -- 定义记录型变量,代表一行--即记录了emp表中一行的类型,使用的时候直接.调用begin  -- 查询语句   select * into dec_emp from emp where empno=‘7839‘;  --使用的时候 dec_emp.sal   变量名.列名   dbms_output.put_line(dec_emp.ename ||‘的薪水是‘|| dec_emp.sal);end;

3.if statements
Three different formats:

格式一:      IF   条件  THEN 语句1;       语句2;       ENDIF;

IF  条件  THEN  语句序列1；       ESLE   2；    END   IF；

格式三(主要使用这种):   IF   条件  THEN 语句;   ELSIF  条件  THEN  语句;   ELSE    语句;   END  IF;

--Determine the number of digits entered on the user's keyboard--input of the receiving keyboard--NUM is the address value that holds the input number on the address valueAccept Num Prompt' Please enter a number ';d Eclare--Define variables to save numbersPnum Number: = #beginifPnum =0  ThenDbms_output.put_line (' The number you have entered is 0 '); elsif Pnum =1  ThenDbms_output.put_line (' The number you have entered is 1 '); elsif Pnum =2  ThenDbms_output.put_line (' The number you have entered is 2 ');ElseDbms_output.put_line (' other numbers ');End if;End;

4. Looping statements

格式一:WHILE   条件LOOP语句序列;END  LOOP;-----------------------------------------------例如:WHILE  total  <= 25000  LOOP.. .total : = total + salary;END  LOOP;

格式二(主要使用这种,EXIT的地方容易理解):LoopEXIT [when   条件];语句序列Endloop

格式三:FOR   I   IN   13    LOOP语句序列 ;END    LOOP

-- 打印1~10的数字declare   1;begin  loop    --循环    --退出条件    exitwhen10;      dbms_output.put_line(pnum);    -- 加1    1;  endloop;end;

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A detailed explanation of basic grammar of PL/SQL Programming (I.)