Pl-sql Programming Basics (2)

First, the control statement

1. If statement

Grammar:

IF < Boolean expressions > Then

PL/SQL and statements

END IF;

Example:

DECLARE  Number: = & n;    BEGIN  IF > 0  Then         dbms_output.put_line (' positive number ')  ; END IF ; END;

Determine if it is a positive integer!

2. If...else ...

Grammar

IF < Boolean expressions > Then

PL/SQL and statements

ELSE

Other statements

END IF;

Example:

DECLAREV_count Number:= &N;BEGIN    IFV_count> 0  ThenDbms_output.put_line ('Positive'); ELSEDbms_output.put_line ('Negative number'); END IF;END;

Determine if it is a positive or negative number!

3, multi-if...else ... Structure

Grammar:

IF < Boolean expressions > Then

PL/SQL and statements

Elsif < Other Boolean expressions > Then

PL/SQL and statements

Elsif < Other Boolean expressions > Then

PL/SQL and statements

ELSE

PL/SQL and statements

END IF;

Example:

DECLAREV_count Number:= &N;BEGIN  IFV_count> 0  ThenDbms_output.put_line ('Positive'); elsif V_count< 0  ThenDbms_output.put_line ('Negative number'); ELSEDbms_output.put_line ('0'); END IF;END;

4. Case statement Syntax:

Format one:

Case conditional expression

When conditional expression result 1 Then

Statement Segment 1

When conditional expression Result 2 Then

Statement segment

......

When conditional expression Results n Then

Statement Segment N

[ELSE statement Segment]

END case;

Example: Show week based on input 1-7

DECLAREV_week Number:= &S;BEGIN   CaseV_week when 1  ThenDbms_output. Put_Line ('Monday');  when 2  ThenDbms_output. Put_Line ('Tuesday');  when 3  ThenDbms_output. Put_Line ('Wednesday');  when 4  ThenDbms_output. Put_Line ('Thursday');  when 5  ThenDbms_output. Put_Line ('Friday');  when 6  ThenDbms_output. Put_Line ('Saturday');  when 7  ThenDbms_output. Put_Line ('Sunday'); ELSEDbms_output. Put_Line ('Input Error'); END  Case;END;

Format two:

Case

When conditional expression 1 then

Statement Segment 1

When conditional expression 2 Then

Statement segment

......

When conditional expression n Then

Statement Segment N

[ELSE statement Segment]

END case;

Example: Based on fractional output a,b,c,d,e

DECLAREV_score Number:= &N;BEGIN   Case     whenV_score>=  -  ThenDbms_output. Put_Line ('A');  whenV_score>=  the  ThenDbms_output. Put_Line ('B');  whenV_score>=  -  ThenDbms_output. Put_Line ('C');  whenV_score>=  -  ThenDbms_output. Put_Line ('D'); ELSEDbms_output. Put_Line ('E'); END  Case;END;

Pl-sql Programming Basics (2)